Central plant control system with asset allocation override

ABSTRACT

A controller for building equipment that operate to provide heating or cooling for a building or campus. The controller includes a processing circuit configured to perform an optimization of an objective function subject to an override constraint to determine amounts of one or more resources to be produced by the building equipment and control the building equipment to produce the amounts of the one or more resources determined by performing the optimization subject to the override constraint. The override constraint overrides an output of the optimization by specifying an override amount of a first resource of the one or more resources to be produced by a first subset of the building equipment.

BACKGROUND

The present disclosure relates generally to a central plant or centralenergy facility configured to serve the energy loads of a building orcampus. The present disclosure relates more particular to a centralplant with an asset allocator configured to determine an optimaldistribution of the energy loads across various subplants of the centralplant.

A central plant typically includes multiple subplants configured toserve different types of energy loads. For example, a central plant mayinclude a chiller subplant configured to serve cooling loads, a heatersubplant configured to serve heating loads, and/or an electricitysubplant configured to serve electric loads. A central plant purchasesresources from utilities to run the subplants to meet the loads.

Some central plants include energy storage. Energy storage may be a tankof water that stores hot water for campus heating, an ice tank forcampus cooling, and/or battery storage. In the presence of real-timepricing from utilities, it may be advantageous to manipulate the timethat a certain resource or energy type is consumed. Instead of producingthe resource exactly when it is required by the load, it can be optimalto produce that resource at a time when the production cost is low,store it, and then use it when the resource needed to produce that typeof energy is more expensive. It can be difficult and challenging tooptimally allocate the energy loads across the assets of the centralplant.

SUMMARY

One implementation of the present disclosure is a controller forbuilding equipment that operate to provide one or more resources to abuilding or campus. The controller includes a processing circuitconfigured to perform an optimization of an objective function subjectto an override constraint to determine amounts of one or more resourcesto be produced by the building equipment and control the buildingequipment to produce the amounts of the one or more resources determinedby performing the optimization subject to the override constraint. Theoverride constraint overrides an output of the optimization byspecifying an override amount of a first resource of the one or moreresources to be produced by a first subset of the building equipment.

In some embodiments, the first subset of the building equipment and asecond subset of the building equipment both operate to produce thefirst resource and contribute toward a total amount of the firstresource required by the building or campus and the optimization isperformed subject to both the override constraint and a secondconstraint that defines the total amount of the first resource requiredby the building or campus.

In some embodiments, performing the optimization subject to both theoverride constraint and the second constraint includes determining asecond amount of the first resource to be produced by the second subsetof the building equipment based on a difference between the total amountof the first resource required by the building or campus and theoverride amount of the first resource to be produced by the first subsetof the building equipment.

In some embodiments, the objective function defines a total cost ofoperating the building equipment over a time period and optimizing theobjective function includes determining amounts of the one or moreresources to be produced by the building equipment that optimize thetotal cost.

In some embodiments, the objective function defines a total resourceconsumption of the building equipment over a time period and optimizingthe objective function includes determining amounts of the one or moreresources to be produced by the building equipment that optimize thetotal resource consumption.

In some embodiments, the optimization of the objective function subjectto the override constraint is a first optimization and the processingcircuit is configured to perform a second optimization of the objectivefunction without the override constraint, calculate a difference betweena first amount of resource consumption or cost resulting from the firstoptimization and a second amount of resource consumption or costresulting from the second optimization, and present, via a userinterface, an override impact indicating the difference between thefirst amount and the second amount.

In some embodiments, the processing circuit is configured to present,via the user interface, an option for a user to select whether to usethe override constraint in view of the override impact, control thebuilding equipment in accordance with a result of the first optimizationin response to the user selecting to use the override constraint, andcontrol the building equipment in accordance with a result of the secondoptimization in response to the user selecting to not use the overrideconstraint.

In some embodiments, the override constraint requires at least one of anamount of the first resource produced by the first subset of buildingequipment to be equal to the override amount, or a difference betweenthe amount of the first resource produced by the first subset ofbuilding equipment and the override amount to be less than a thresholdvalue.

Another implementation of the present disclosure is a method foroperating building equipment to provide one or more resources to abuilding or campus. The method includes receiving a user inputspecifying an override amount of a first resource to be produced by afirst subset of the building equipment, generating an overrideconstraint based on the user input, performing an optimization of anobjective function subject to the override constraint to determineamounts of one or more resources, including the first resource, to beproduced by the building equipment, and controlling the buildingequipment to produce the amounts of the one or more resources determinedby performing the optimization subject to the override constraint. Theoverride constraint overrides an output of the optimization.

In some embodiments, the first subset of the building equipment and asecond subset of the building equipment both operate to produce thefirst resource and contribute toward a total amount of the firstresource required by the building or campus and the optimization isperformed subject to both the override constraint and a secondconstraint that defines the total amount of the first resource requiredby the building or campus.

In some embodiments, performing the optimization subject to both theoverride constraint and the second constraint includes determining asecond amount of the first resource to be produced by the second subsetof the building equipment based on a difference between the total amountof the first resource required by the building or campus and theoverride amount of the first resource to be produced by the first subsetof the building equipment.

In some embodiments, the objective function defines a total cost ofoperating the building equipment over a time period and optimizing theobjective function includes determining amounts of the one or moreresources to be produced by the building equipment that optimize thetotal cost.

In some embodiments, the objective function defines a total resourceconsumption of the building equipment over a time period and optimizingthe objective function includes determining amounts of the one or moreresources to be produced by the building equipment that optimize thetotal resource consumption.

In some embodiments, the optimization of the objective function subjectto the override constraint is a first optimization. The method furtherincludes performing a second optimization of the objective functionwithout the override constraint, calculating a difference between afirst amount of resource consumption or cost resulting from the firstoptimization and a second amount of resource consumption or costresulting from the second optimization, and presenting, via a userinterface, an override impact indicating the difference between thefirst amount and the second amount.

In some embodiments, the method further includes presenting, via theuser interface, an option for a user to select whether to use theoverride constraint in view of the override impact, controlling thebuilding equipment in accordance with a result of the first optimizationin response to the user selecting to use the override constraint, andcontrolling the building equipment in accordance with a result of thesecond optimization in response to the user selecting to not use theoverride constraint.

In some embodiments, the override constraint requires at least one of anamount of the first resource produced by the first subset of buildingequipment to be equal to the override amount or a difference between theamount of the first resource produced by the first subset of buildingequipment and the override amount to be less than a threshold value.

Another implementation of the present disclosure is a controller forbuilding equipment that operate to provide one or more resources to abuilding or campus. The controller includes a processing circuitconfigured to perform a first optimization of an objective function todetermine first amounts of one or more resources to be produced by thebuilding equipment as a result of the first optimization receive a userinput specifying an override amount of a first resource of the one ormore resources to be produced by a first subset of the buildingequipment, perform a second optimization of the objective function,subject to an override constraint based on the user input, to determinesecond amounts of one or more resources to be produced by the buildingequipment as a result of the second optimization, and control thebuilding equipment in accordance with the result of the firstoptimization or the result of the second optimization. The overrideconstraint overrides a portion of the result of the first optimization.

In some embodiments, the processing circuit is configured to calculate adifference between a first amount of resource consumption or costresulting from the first optimization result and a second amount ofresource consumption or cost resulting from the second optimization andpresent, via a user interface, an override impact indicating thedifference between the first amount and the second amount.

In some embodiments, the processing circuit is configured to present,via the user interface, an option for a user to select whether to usethe override constraint in view of the override impact, control thebuilding equipment in accordance with the result of the firstoptimization in response to the user selecting to not use the overrideconstraint, and control the building equipment in accordance with theresult of the second optimization in response to the user selecting touse the override constraint.

In some embodiments, the first subset of the building equipment and asecond subset of the building equipment both operate to produce thefirst resource and contribute toward a total amount of the firstresource required by the building or campus, the second optimization isperformed subject to both the override constraint and a secondconstraint that defines the total amount of the first resource requiredby the building or campus, and performing the second optimizationsubject to both the override constraint and the second constraintincludes determining a second amount of the first resource to beproduced by the second subset of the building equipment based on adifference between the total amount of the first resource required bythe building or campus and the override amount of the first resource tobe produced by the first subset of the building equipment.

BRIEF DESCRIPTION OF THE DRAWINGS

Various objects, aspects, features, and advantages of the disclosurewill become more apparent and better understood by referring to thedetailed description taken in conjunction with the accompanyingdrawings, in which like reference characters identify correspondingelements throughout. In the drawings, like reference numbers generallyindicate identical, functionally similar, and/or structurally similarelements.

FIG. 1 is a drawing of a building equipped with a HVAC system, accordingto some embodiments.

FIG. 2 is a block diagram of a central plant which can be used to servethe energy loads of the building of FIG. 1, according to someembodiments.

FIG. 3 is a block diagram of an airside system which can be implementedin the building of FIG. 1, according to some embodiments.

FIG. 4 is a block diagram of an asset allocation system includingsources, subplants, storage, sinks, and an asset allocator configured tooptimize the allocation of these assets, according to according to someembodiments.

FIG. 5 is a block diagram of a central plant controller in which theasset allocator of FIG. 4 can be implemented, according to someembodiments.

FIG. 6 is a block diagram of the asset allocator of FIG. 4 in greaterdetail, according to some embodiments.

FIG. 7 is a flow diagram illustrating a method of optimizing a costfunction to determine the allocation of assets and controlling subplantsbased on the results of the optimization, according to some embodiments.

FIG. 8 is a flow diagram illustrating a method of presenting a user withan override impact which defines the difference between two optimizedcost functions, according to some embodiments.

FIG. 9 is a graph illustrating the production and storage load scheduleacross multiple subplants without a user override, according to someembodiments.

FIG. 10 is a graph illustrating the production and storage load scheduleacross multiple subplants with a user override and presenting theoverride cost impact, according to some embodiments.

DETAILED DESCRIPTION Overview

Referring generally to the FIGURES, a central plant with an assetallocator and components thereof are shown, according to variousexemplary embodiments. The asset allocator can be configured to manageenergy assets such as central plant equipment, battery storage, andother types of equipment configured to serve the energy loads of abuilding. The asset allocator can determine an optimal distribution ofenergy loads (e.g., heating, cooling, electricity) across differentsubplants (i.e., equipment groups) of the central plant capable ofproducing that type of energy.

In some embodiments, the asset allocator can be configured to controlthe distribution, production, storage, and usage of resources in thecentral plant. The asset allocator can be configured to minimize theeconomic cost (or maximize the economic value) of operating the centralplant over a duration of an optimization horizon. The economic cost maybe defined by a cost function J(x) that expresses economic cost as afunction of the control decisions made by the asset allocator. The costfunction J(x) may account for the cost of resources purchased fromvarious sources, as well as the revenue generated by selling resources(e.g., to an energy grid) or participating in incentive programs. Insome embodiments, the asset allocator can be configured to minimize theresource consumption associated with operating the central plant overthe duration of the optimization horizon. For example, asset allocatormay be configured to minimize the total amount of each resource obtainedfrom a plurality of sources over the duration of the optimizationhorizon, regardless of cost or price.

The asset allocator can be configured to define various sources,subplants, storage, and sinks. These four categories of objects definethe assets of a central plant and their interaction with the outsideworld. Sources may include commodity markets or other suppliers fromwhich resources such as electricity, water, natural gas, and otherresources can be purchased or obtained. Sinks may include the requestedloads of a building or campus as well as other types of resourceconsumers. Subplants are the main assets of a central plant. Subplantscan be configured to convert resource types, making it possible tobalance requested loads from a building or campus using resourcespurchased from the sources. Storage can be configured to store energy orother types of resources for later use.

In some embodiments, the asset allocator performs an optimizationprocess to determine an optimal set of control decisions for each timestep within the optimization horizon. The control decisions may include,for example, an optimal amount of each resource to purchase from thesources, an optimal amount of each resource to produce or convert usingthe subplants, an optimal amount of each resource to store or removefrom storage, an optimal amount of each resource to sell to resourcespurchasers, and/or an optimal amount of each resource to provide toother sinks. In some embodiments, the asset allocator is configured tooptimally dispatch all campus energy assets (i.e., the central plantequipment) in order to meet the requested heating, cooling, andelectrical loads of the campus for each time step within theoptimization horizon.

In some embodiments, the asset allocator may allow a user to override anamount of one or more resources produced or converted by one or moresubplants. The asset allocator may perform an optimization process todetermine an optimal set of control decisions, subject to the overrideamount provided by the user. In some embodiments, the asset allocatorprovides a cost impact associated with operating the central plantsubject to the override. The cost impact may be the difference between acost of operating the central plant subject to override and a cost ofoperating the central plant not subject to the override amount. In someembodiments, the user may be presented, via a user interface, with thecost impact as a dollar value. These and other features of the assetallocator are described in greater detail below.

Building and HVAC System

Referring now to FIG. 1, a perspective view of a building 10 is shown.Building 10 can be served by a building management system (BMS). A BMSis, in general, a system of devices configured to control, monitor, andmanage equipment in or around a building or building area. A BMS caninclude, for example, a HVAC system, a security system, a lightingsystem, a fire alerting system, any other system that is capable ofmanaging building functions or devices, or any combination thereof.

The BMS that serves building 10 may include a HVAC system 100. HVACsystem 100 can include a plurality of HVAC devices (e.g., heaters,chillers, air handling units, pumps, fans, thermal energy storage, etc.)configured to provide heating, cooling, ventilation, or other servicesfor building 10. For example, HVAC system 100 is shown to include awaterside system 120 and an airside system 130. Waterside system 120 mayprovide a heated or chilled fluid to an air handling unit of airsidesystem 130. Airside system 130 may use the heated or chilled fluid toheat or cool an airflow provided to building 10. In some embodiments,waterside system 120 can be replaced with or supplemented by a centralplant or central energy facility (described in greater detail withreference to FIG. 2). An example of an airside system which can be usedin HVAC system 100 is described in greater detail with reference to FIG.3.

HVAC system 100 is shown to include a chiller 102, a boiler 104, and arooftop air handling unit (AHU) 106. Waterside system 120 may use boiler104 and chiller 102 to heat or cool a working fluid (e.g., water,glycol, etc.) and may circulate the working fluid to AHU 106. In variousembodiments, the HVAC devices of waterside system 120 can be located inor around building 10 (as shown in FIG. 1) or at an offsite locationsuch as a central plant (e.g., a chiller plant, a steam plant, a heatplant, etc.). The working fluid can be heated in boiler 104 or cooled inchiller 102, depending on whether heating or cooling is required inbuilding 10. Boiler 104 may add heat to the circulated fluid, forexample, by burning a combustible material (e.g., natural gas) or usingan electric heating element. Chiller 102 may place the circulated fluidin a heat exchange relationship with another fluid (e.g., a refrigerant)in a heat exchanger (e.g., an evaporator) to absorb heat from thecirculated fluid. The working fluid from chiller 102 and/or boiler 104can be transported to AHU 106 via piping 108.

AHU 106 may place the working fluid in a heat exchange relationship withan airflow passing through AHU 106 (e.g., via one or more stages ofcooling coils and/or heating coils). The airflow can be, for example,outside air, return air from within building 10, or a combination ofboth. AHU 106 may transfer heat between the airflow and the workingfluid to provide heating or cooling for the airflow. For example, AHU106 can include one or more fans or blowers configured to pass theairflow over or through a heat exchanger containing the working fluid.The working fluid may then return to chiller 102 or boiler 104 viapiping 110.

Airside system 130 may deliver the airflow supplied by AHU 106 (i.e.,the supply airflow) to building 10 via air supply ducts 112 and mayprovide return air from building 10 to AHU 106 via air return ducts 114.In some embodiments, airside system 130 includes multiple variable airvolume (VAV) units 116. For example, airside system 130 is shown toinclude a separate VAV unit 116 on each floor or zone of building 10.VAV units 116 can include dampers or other flow control elements thatcan be operated to control an amount of the supply airflow provided toindividual zones of building 10. In other embodiments, airside system130 delivers the supply airflow into one or more zones of building 10(e.g., via supply ducts 112) without using intermediate VAV units 116 orother flow control elements. AHU 106 can include various sensors (e.g.,temperature sensors, pressure sensors, etc.) configured to measureattributes of the supply airflow. AHU 106 may receive input from sensorslocated within AHU 106 and/or within the building zone and may adjustthe flow rate, temperature, or other attributes of the supply airflowthrough AHU 106 to achieve setpoint conditions for the building zone.

Central Plant

Referring now to FIG. 2, a block diagram of a central plant 200 isshown, according to some embodiments. In various embodiments, centralplant 200 can supplement or replace waterside system 120 in HVAC system100 or can be implemented separate from HVAC system 100. Whenimplemented in HVAC system 100, central plant 200 can include a subsetof the HVAC devices in HVAC system 100 (e.g., boiler 104, chiller 102,pumps, valves, etc.) and may operate to supply a heated or chilled fluidto AHU 106. The HVAC devices of central plant 200 can be located withinbuilding 10 (e.g., as components of waterside system 120) or at anoffsite location such as a central energy facility that serves multiplebuildings.

Central plant 200 is shown to include a plurality of subplants 202-208.Subplants 202-208 can be configured to convert energy or resource types(e.g., water, natural gas, electricity, etc.). For example, subplants202-208 are shown to include a heater subplant 202, a heat recoverychiller subplant 204, a chiller subplant 206, and a cooling towersubplant 208. In some embodiments, subplants 202-208 consume resourcespurchased from utilities to serve the energy loads (e.g., hot water,cold water, electricity, etc.) of a building or campus. For example,heater subplant 202 can be configured to heat water in a hot water loop214 that circulates the hot water between heater subplant 202 andbuilding 10. Similarly, chiller subplant 206 can be configured to chillwater in a cold water loop 216 that circulates the cold water betweenchiller subplant 206 building 10.

Heat recovery chiller subplant 204 can be configured to transfer heatfrom cold water loop 216 to hot water loop 214 to provide additionalheating for the hot water and additional cooling for the cold water.Condenser water loop 218 may absorb heat from the cold water in chillersubplant 206 and reject the absorbed heat in cooling tower subplant 208or transfer the absorbed heat to hot water loop 214. In variousembodiments, central plant 200 can include an electricity subplant(e.g., one or more electric generators) configured to generateelectricity or any other type of subplant configured to convert energyor resource types.

Hot water loop 214 and cold water loop 216 may deliver the heated and/orchilled water to air handlers located on the rooftop of building 10(e.g., AHU 106) or to individual floors or zones of building 10 (e.g.,VAV units 116). The air handlers push air past heat exchangers (e.g.,heating coils or cooling coils) through which the water flows to provideheating or cooling for the air. The heated or cooled air can bedelivered to individual zones of building 10 to serve thermal energyloads of building 10. The water then returns to subplants 202-208 toreceive further heating or cooling.

Although subplants 202-208 are shown and described as heating andcooling water for circulation to a building, it is understood that anyother type of working fluid (e.g., glycol, CO₂, etc.) can be used inplace of or in addition to water to serve thermal energy loads. In otherembodiments, subplants 202-208 may provide heating and/or coolingdirectly to the building or campus without requiring an intermediateheat transfer fluid. These and other variations to central plant 200 arewithin the teachings of the present disclosure.

Each of subplants 202-208 can include a variety of equipment configuredto facilitate the functions of the subplant. For example, heatersubplant 202 is shown to include a plurality of heating elements 220(e.g., boilers, electric heaters, etc.) configured to add heat to thehot water in hot water loop 214. Heater subplant 202 is also shown toinclude several pumps 222 and 224 configured to circulate the hot waterin hot water loop 214 and to control the flow rate of the hot waterthrough individual heating elements 220. Chiller subplant 206 is shownto include a plurality of chillers 232 configured to remove heat fromthe cold water in cold water loop 216. Chiller subplant 206 is alsoshown to include several pumps 234 and 236 configured to circulate thecold water in cold water loop 216 and to control the flow rate of thecold water through individual chillers 232.

Heat recovery chiller subplant 204 is shown to include a plurality ofheat recovery heat exchangers 226 (e.g., refrigeration circuits)configured to transfer heat from cold water loop 216 to hot water loop214. Heat recovery chiller subplant 204 is also shown to include severalpumps 228 and 230 configured to circulate the hot water and/or coldwater through heat recovery heat exchangers 226 and to control the flowrate of the water through individual heat recovery heat exchangers 226.Cooling tower subplant 208 is shown to include a plurality of coolingtowers 238 configured to remove heat from the condenser water incondenser water loop 218. Cooling tower subplant 208 is also shown toinclude several pumps 240 configured to circulate the condenser water incondenser water loop 218 and to control the flow rate of the condenserwater through individual cooling towers 238.

In some embodiments, one or more of the pumps in central plant 200(e.g., pumps 222, 224, 228, 230, 234, 236, and/or 240) or pipelines incentral plant 200 include an isolation valve associated therewith.Isolation valves can be integrated with the pumps or positioned upstreamor downstream of the pumps to control the fluid flows in central plant200. In various embodiments, central plant 200 can include more, fewer,or different types of devices and/or subplants based on the particularconfiguration of central plant 200 and the types of loads served bycentral plant 200.

Still referring to FIG. 2, central plant 200 is shown to include hotthermal energy storage (TES) 210 and cold thermal energy storage (TES)212. Hot TES 210 and cold TES 212 can be configured to store hot andcold thermal energy for subsequent use. For example, hot TES 210 caninclude one or more hot water storage tanks 242 configured to store thehot water generated by heater subplant 202 or heat recovery chillersubplant 204. Hot TES 210 may also include one or more pumps or valvesconfigured to control the flow rate of the hot water into or out of hotTES tank 242.

Similarly, cold TES 212 can include one or more cold water storage tanks244 configured to store the cold water generated by chiller subplant 206or heat recovery chiller subplant 204. Cold TES 212 may also include oneor more pumps or valves configured to control the flow rate of the coldwater into or out of cold TES tanks 244. In some embodiments, centralplant 200 includes electrical energy storage (e.g., one or morebatteries) or any other type of device configured to store resources.The stored resources can be purchased from utilities, generated bycentral plant 200, or otherwise obtained from any source.

Airside System

Referring now to FIG. 3, a block diagram of an airside system 300 isshown, according to some embodiments. In various embodiments, airsidesystem 300 may supplement or replace airside system 130 in HVAC system100 or can be implemented separate from HVAC system 100. Whenimplemented in HVAC system 100, airside system 300 can include a subsetof the HVAC devices in HVAC system 100 (e.g., AHU 106, VAV units 116,ducts 112-114, fans, dampers, etc.) and can be located in or aroundbuilding 10. Airside system 300 may operate to heat or cool an airflowprovided to building 10 using a heated or chilled fluid provided bycentral plant 200.

Airside system 300 is shown to include an economizer-type air handlingunit (AHU) 302. Economizer-type AHUs vary the amount of outside air andreturn air used by the air handling unit for heating or cooling. Forexample, AHU 302 may receive return air 304 from building zone 306 viareturn air duct 308 and may deliver supply air 310 to building zone 306via supply air duct 312. In some embodiments, AHU 302 is a rooftop unitlocated on the roof of building 10 (e.g., AHU 106 as shown in FIG. 1) orotherwise positioned to receive both return air 304 and outside air 314.AHU 302 can be configured to operate exhaust air damper 316, mixingdamper 318, and outside air damper 320 to control an amount of outsideair 314 and return air 304 that combine to form supply air 310. Anyreturn air 304 that does not pass through mixing damper 318 can beexhausted from AHU 302 through exhaust damper 316 as exhaust air 322.

Each of dampers 316-320 can be operated by an actuator. For example,exhaust air damper 316 can be operated by actuator 324, mixing damper318 can be operated by actuator 326, and outside air damper 320 can beoperated by actuator 328. Actuators 324-328 may communicate with an AHUcontroller 330 via a communications link 332. Actuators 324-328 mayreceive control signals from AHU controller 330 and may provide feedbacksignals to AHU controller 330. Feedback signals can include, forexample, an indication of a current actuator or damper position, anamount of torque or force exerted by the actuator, diagnosticinformation (e.g., results of diagnostic tests performed by actuators324-328), status information, commissioning information, configurationsettings, calibration data, and/or other types of information or datathat can be collected, stored, or used by actuators 324-328. AHUcontroller 330 can be an economizer controller configured to use one ormore control algorithms (e.g., state-based algorithms, extremum seekingcontrol (ESC) algorithms, proportional-integral (PI) control algorithms,proportional-integral-derivative (PID) control algorithms, modelpredictive control (MPC) algorithms, feedback control algorithms, etc.)to control actuators 324-328.

Still referring to FIG. 3, AHU 302 is shown to include a cooling coil334, a heating coil 336, and a fan 338 positioned within supply air duct312. Fan 338 can be configured to force supply air 310 through coolingcoil 334 and/or heating coil 336 and provide supply air 310 to buildingzone 306. AHU controller 330 may communicate with fan 338 viacommunications link 340 to control a flow rate of supply air 310. Insome embodiments, AHU controller 330 controls an amount of heating orcooling applied to supply air 310 by modulating a speed of fan 338.

Cooling coil 334 may receive a chilled fluid from central plant 200(e.g., from cold water loop 216) via piping 342 and may return thechilled fluid to central plant 200 via piping 344. Valve 346 can bepositioned along piping 342 or piping 344 to control a flow rate of thechilled fluid through cooling coil 334. In some embodiments, coolingcoil 334 includes multiple stages of cooling coils that can beindependently activated and deactivated (e.g., by AHU controller 330, byBMS controller 366, etc.) to modulate an amount of cooling applied tosupply air 310.

Heating coil 336 may receive a heated fluid from central plant 200(e.g., from hot water loop 214) via piping 348 and may return the heatedfluid to central plant 200 via piping 350. Valve 352 can be positionedalong piping 348 or piping 350 to control a flow rate of the heatedfluid through heating coil 336. In some embodiments, heating coil 336includes multiple stages of heating coils that can be independentlyactivated and deactivated (e.g., by AHU controller 330, by BMScontroller 366, etc.) to modulate an amount of heating applied to supplyair 310.

Each of valves 346 and 352 can be controlled by an actuator. Forexample, valve 346 can be controlled by actuator 354 and valve 352 canbe controlled by actuator 356. Actuators 354-356 may communicate withAHU controller 330 via communications links 358-360. Actuators 354-356may receive control signals from AHU controller 330 and may providefeedback signals to controller 330. In some embodiments, AHU controller330 receives a measurement of the supply air temperature from atemperature sensor 362 positioned in supply air duct 312 (e.g.,downstream of cooling coil 334 and/or heating coil 336). AHU controller330 may also receive a measurement of the temperature of building zone306 from a temperature sensor 364 located in building zone 306.

In some embodiments, AHU controller 330 operates valves 346 and 352 viaactuators 354-356 to modulate an amount of heating or cooling providedto supply air 310 (e.g., to achieve a setpoint temperature for supplyair 310 or to maintain the temperature of supply air 310 within asetpoint temperature range). The positions of valves 346 and 352 affectthe amount of heating or cooling provided to supply air 310 by coolingcoil 334 or heating coil 336 and may correlate with the amount of energyconsumed to achieve a desired supply air temperature. AHU 330 maycontrol the temperature of supply air 310 and/or building zone 306 byactivating or deactivating coils 334-336, adjusting a speed of fan 338,or a combination of both.

Still referring to FIG. 3, airside system 300 is shown to include abuilding management system (BMS) controller 366 and a client device 368.BMS controller 366 can include one or more computer systems (e.g.,servers, supervisory controllers, subsystem controllers, etc.) thatserve as system level controllers, application or data servers, headnodes, or master controllers for airside system 300, central plant 200,HVAC system 100, and/or other controllable systems that serve building10. BMS controller 366 may communicate with multiple downstream buildingsystems or subsystems (e.g., HVAC system 100, a security system, alighting system, central plant 200, etc.) via a communications link 370according to like or disparate protocols (e.g., LON, BACnet, etc.). Invarious embodiments, AHU controller 330 and BMS controller 366 can beseparate (as shown in FIG. 3) or integrated. In an integratedimplementation, AHU controller 330 can be a software module configuredfor execution by a processor of BMS controller 366.

In some embodiments, AHU controller 330 receives information from BMScontroller 366 (e.g., commands, setpoints, operating boundaries, etc.)and provides information to BMS controller 366 (e.g., temperaturemeasurements, valve or actuator positions, operating statuses,diagnostics, etc.). For example, AHU controller 330 may provide BMScontroller 366 with temperature measurements from temperature sensors362-364, equipment on/off states, equipment operating capacities, and/orany other information that can be used by BMS controller 366 to monitoror control a variable state or condition within building zone 306.

Client device 368 can include one or more human-machine interfaces orclient interfaces (e.g., graphical user interfaces, reportinginterfaces, text-based computer interfaces, client-facing web services,web servers that provide pages to web clients, etc.) for controlling,viewing, or otherwise interacting with HVAC system 100, its subsystems,and/or devices. Client device 368 can be a computer workstation, aclient terminal, a remote or local interface, or any other type of userinterface device. Client device 368 can be a stationary terminal or amobile device. For example, client device 368 can be a desktop computer,a computer server with a user interface, a laptop computer, a tablet, asmartphone, a PDA, or any other type of mobile or non-mobile device.Client device 368 may communicate with BMS controller 366 and/or AHUcontroller 330 via communications link 372.

Asset Allocation System

Referring now to FIG. 4, a block diagram of an asset allocation system400 is shown, according to an exemplary embodiment. Asset allocationsystem 400 can be configured to manage energy assets such as centralplant equipment, battery storage, and other types of building equipmentconfigured to serve the energy loads of a building. In some embodiments,building equipment can include equipment within a building or equipmentwithin an off-site plant that operate to provide various resources to abuilding or campus. For example, building equipment may includebatteries, thermal energy storage, chillers, hot water generators,combustion turbines, steam generators, electric generators, etc.

Asset allocation system 400 can determine an optimal distribution ofheating, cooling, electricity, and energy loads across differentsubplants (i.e., building equipment groups) capable of producing thattype of energy. In some embodiments, asset allocation system 400 isimplemented as a component of central plant 200 and interacts with theequipment of central plant 200 in an online operational environment(e.g., performing real-time control of the central plant equipment). Inother embodiments, asset allocation system 400 can be implemented as acomponent of a planning tool and can be configured to simulate theoperation of a central plant over a predetermined time period forplanning, budgeting, and/or design considerations.

Asset allocation system 400 is shown to include sources 410, subplants420, storage 430, and sinks 440. These four categories of objects definethe assets of a central plant and their interaction with the outsideworld. Sources 410 may include commodity markets or other suppliers fromwhich resources such as electricity, water, natural gas, and otherresources can be purchased or obtained. Sources 410 may provideresources that can be used by asset allocation system 400 to satisfy thedemand of a building or campus. For example, sources 410 are shown toinclude an electric utility 411, a water utility 412, a natural gasutility 413, a photovoltaic (PV) field (e.g., a collection of solarpanels), an energy market 415, and source M 416, where M is the totalnumber of sources 410. Resources purchased from sources 410 can be usedby subplants 420 to produce generated resources (e.g., hot water, coldwater, electricity, steam, etc.), stored in storage 430 for later use,or provided directly to sinks 440.

Subplants 420 are shown to include a heater subplant 421, a chillersubplant 422, a heat recovery chiller subplant 423, a steam subplant424, an electricity subplant 425, and subplant N, where N is the totalnumber of subplants 420. In some embodiments, subplants 420 include someor all of the subplants of central plant 200, as described withreference to FIG. 2. For example, subplants 420 can include heatersubplant 202, heat recovery chiller subplant 204, chiller subplant 206,and/or cooling tower subplant 208.

Subplants 420 can be configured to convert resource types, making itpossible to balance requested loads from the building or campus usingresources purchased from sources 410. For example, heater subplant 421may be configured to generate hot thermal energy (e.g., hot water) byheating water using electricity or natural gas. Chiller subplant 422 maybe configured to generate cold thermal energy (e.g., cold water) bychilling water using electricity. Heat recovery chiller subplant 423 maybe configured to generate hot thermal energy and cold thermal energy byremoving heat from one water supply and adding the heat to another watersupply. Steam subplant 424 may be configured to generate steam byboiling water using electricity or natural gas. Electricity subplant 425may be configured to generate electricity using mechanical generators(e.g., a steam turbine, a gas-powered generator, etc.) or other types ofelectricity-generating equipment (e.g., photovoltaic equipment,hydroelectric equipment, etc.).

The input resources used by subplants 420 may be provided by sources410, retrieved from storage 430, and/or generated by other subplants420. For example, steam subplant 424 may produce steam as an outputresource. Electricity subplant 425 may include a steam turbine that usesthe steam generated by steam subplant 424 as an input resource togenerate electricity. The output resources produced by subplants 420 maybe stored in storage 430, provided to sinks 440, and/or used by othersubplants 420. For example, the electricity generated by electricitysubplant 425 may be stored in electrical energy storage 433, used bychiller subplant 422 to generate cold thermal energy, used to satisfythe electric load 445 of a building, or sold to resource purchasers 441.

Storage 430 can be configured to store energy or other types ofresources for later use. Each type of storage within storage 430 may beconfigured to store a different type of resource. For example, storage430 is shown to include hot thermal energy storage 431 (e.g., one ormore hot water storage tanks), cold thermal energy storage 432 (e.g.,one or more cold thermal energy storage tanks), electrical energystorage 433 (e.g., one or more batteries), and resource type P storage434, where P is the total number of storage 430. In some embodiments,storage 430 include some or all of the storage of central plant 200, asdescribed with reference to FIG. 2. In some embodiments, storage 430includes the heat capacity of the building served by the central plant.The resources stored in storage 430 may be purchased directly fromsources or generated by subplants 420.

In some embodiments, storage 430 is used by asset allocation system 400to take advantage of price-based demand response (PBDR) programs. PBDRprograms encourage consumers to reduce consumption when generation,transmission, and distribution costs are high. PBDR programs aretypically implemented (e.g., by sources 410) in the form of energyprices that vary as a function of time. For example, some utilities mayincrease the price per unit of electricity during peak usage hours toencourage customers to reduce electricity consumption during peak times.Some utilities also charge consumers a separate demand charge based onthe maximum rate of electricity consumption at any time during apredetermined demand charge period.

Advantageously, storing energy and other types of resources in storage430 allows for the resources to be purchased at times when the resourcesare relatively less expensive (e.g., during non-peak electricity hours)and stored for use at times when the resources are relatively moreexpensive (e.g., during peak electricity hours). Storing resources instorage 430 also allows the resource demand of the building or campus tobe shifted in time. For example, resources can be purchased from sources410 at times when the demand for heating or cooling is low andimmediately converted into hot or cold thermal energy by subplants 420.The thermal energy can be stored in storage 430 and retrieved at timeswhen the demand for heating or cooling is high. This allows assetallocation system 400 to smooth the resource demand of the building orcampus and reduces the maximum required capacity of subplants 420.Smoothing the demand also asset allocation system 400 to reduce the peakelectricity consumption, which results in a lower demand charge.

In some embodiments, storage 430 is used by asset allocation system 400to take advantage of incentive-based demand response (IBDR) programs.IBDR programs provide incentives to customers who have the capability tostore energy, generate energy, or curtail energy usage upon request.Incentives are typically provided in the form of monetary revenue paidby sources 410 or by an independent service operator (ISO). IBDRprograms supplement traditional utility-owned generation, transmission,and distribution assets with additional options for modifying demandload curves. For example, stored energy can be sold to resourcepurchasers 441 or an energy grid 442 to supplement the energy generatedby sources 410. In some instances, incentives for participating in anIBDR program vary based on how quickly a system can respond to a requestto change power output/consumption. Faster responses may be compensatedat a higher level. Advantageously, electrical energy storage 433 allowssystem 400 to quickly respond to a request for electric power by rapidlydischarging stored electrical energy to energy grid 442.

Sinks 440 may include the requested loads of a building or campus aswell as other types of resource consumers. For example, sinks 440 areshown to include resource purchasers 441, an energy grid 442, a hotwater load 443, a cold water load 444, an electric load 445, and sink Q,where Q is the total number of sinks 440. A building may consume variousresources including, for example, hot thermal energy (e.g., hot water),cold thermal energy (e.g., cold water), and/or electrical energy. Insome embodiments, the resources are consumed by equipment or subsystemswithin the building (e.g., HVAC equipment, lighting, computers and otherelectronics, etc.). The consumption of each sink 440 over theoptimization horizon can be supplied as an input to asset allocationsystem 400 or predicted by asset allocation system 400. Sinks 440 canreceive resources directly from sources 410, from subplants 420, and/orfrom storage 430.

Still referring to FIG. 4, asset allocation system 400 is shown toinclude an asset allocator 402. Asset allocator 402 can be implementedas part of a controller, computing system, cloud computing resource,etc., for example as shown in FIG. 5 and described with referencethereto. Asset allocator 402 may be configured to control thedistribution, production, storage, and usage of resources in assetallocation system 400. In some embodiments, asset allocator 402 performsan optimization process determine an optimal set of control decisionsfor each time step within an optimization horizon. The control decisionsmay include, for example, an optimal amount of each resource to purchasefrom sources 410, an optimal amount of each resource to produce orconvert using subplants 420, an optimal amount of each resource to storeor remove from storage 430, an optimal amount of each resource to sellto resources purchasers 441 or energy grid 440, and/or an optimal amountof each resource to provide to other sinks 440. In some embodiments, thecontrol decisions include an optimal amount of each input resource andoutput resource for each of subplants 420.

In some embodiments, asset allocator 402 is configured to optimallydispatch all campus energy assets in order to meet the requestedheating, cooling, and electrical loads of the campus for each time stepwithin an optimization horizon or optimization horizon of duration h.Instead of focusing on only the typical HVAC energy loads, the conceptis extended to the concept of resource. Throughout this disclosure, theterm “resource” is used to describe any type of commodity purchased fromsources 410, used or produced by subplants 420, stored or discharged bystorage 430, or consumed by sinks 440. For example, water may beconsidered a resource that is consumed by chillers, heaters, or coolingtowers during operation. This general concept of a resource can beextended to chemical processing plants where one of the resources is theproduct that is being produced by the chemical processing plat.

Asset allocator 402 can be configured to operate the equipment of assetallocation system 400 to ensure that a resource balance is maintained ateach time step of the optimization horizon. This resource balance isshown in the following equation:

Σx _(time)=0∀ resources, ∀ time∈horizon

where the sum is taken over all producers and consumers of a givenresource (i.e., all of sources 410, subplants 420, storage 430, andsinks 440) and time is the time index. Each time element represents aperiod of time during which the resource productions, requests,purchases, etc. are assumed constant. Asset allocator 402 may ensurethat this equation is satisfied for all resources regardless of whetherthat resource is required by the building or campus. For example, someof the resources produced by subplants 420 may be intermediate resourcesthat function only as inputs to other subplants 420.

In some embodiments, the resources balanced by asset allocator 402include multiple resources of the same type (e.g., multiple chilledwater resources, multiple electricity resources, etc.). Definingmultiple resources of the same type may allow asset allocator 402 tosatisfy the resource balance given the physical constraints andconnections of the central plant equipment. For example, suppose acentral plant has multiple chillers and multiple cold water storagetanks, with each chiller physically connected to a different cold waterstorage tank (i.e., chiller A is connected to cold water storage tank A,chiller B is connected to cold water storage tank B, etc.). Given thatonly one chiller can supply cold water to each cold water storage tank,a different cold water resource can be defined for the output of eachchiller. This allows asset allocator 402 to ensure that the resourcebalance is satisfied for each cold water resource without attempting toallocate resources in a way that is physically impossible (e.g., storingthe output of chiller A in cold water storage tank B, etc.).

In some embodiments, asset allocator 402 may be configured to minimizethe economic cost (or maximize the economic value) of operating assetallocation system 400 over the duration of the optimization horizon. Theeconomic cost may be defined by a cost function J(x) that expresseseconomic cost as a function of the control decisions made by assetallocator 402. The cost function J(x) may account for the cost ofresources purchased from sources 410, as well as the revenue generatedby selling resources to resource purchasers 441 or energy grid 442 orparticipating in incentive programs. The cost optimization performed byasset allocator 402 can be expressed as:

$\underset{x}{argmin}{J(x)}$

where J(x) is defined as follows:

${J(x)} = {{\sum\limits_{sources}{\sum\limits_{horizon}{{cost}\left( {{{purch}ase_{{resource},{{tim}e}}},{time}} \right)}}} - {\sum\limits_{incentives}{\sum\limits_{horizon}{{revenue}({ReservationAmount})}}}}$

The first term in the cost function J(x) represents the total cost ofall resources purchased over the optimization horizon. Resources caninclude, for example, water, electricity, natural gas, or other types ofresources purchased from a utility or other source 410. The second termin the cost function J(x) represents the total revenue generated byparticipating in incentive programs (e.g., IBDR programs) over theoptimization horizon. The revenue may be based on the amount of powerreserved for participating in the incentive programs. Accordingly, thetotal cost function represents the total cost of resources purchasedminus any revenue generated from participating in incentive programs. Insome embodiments, asset allocator 402 may be configured to minimize thetotal amount of each resource obtained from sources 410 over theduration of the optimization horizon, regardless of cost or price, tominimize the resource consumption of asset allocation system 400.

Each of subplants 420 and storage 430 may include building equipmentthat can be controlled by asset allocator 402 to optimize theperformance of asset allocation system 400. Subplant equipment mayinclude, for example, heating devices, chillers, heat recovery heatexchangers, cooling towers, energy storage devices, pumps, valves,and/or other devices of subplants 420 and storage 430. Individualdevices of subplants 420 can be turned on or off to adjust the resourceproduction of each subplant 420. In some embodiments, individual devicesof subplants 420 can be operated at variable capacities (e.g., operatinga chiller at 10% capacity or 60% capacity) according to an operatingsetpoint received from asset allocator 402. Asset allocator 402 cancontrol the equipment of subplants 420 and storage 430 to adjust theamount of each resource purchased, consumed, and/or produced by system400.

In some embodiments, asset allocator 402 minimizes the cost functionwhile participating in PBDR programs, IBDR programs, or simultaneouslyin both PBDR and IBDR programs. For the IBDR programs, asset allocator402 may use statistical estimates of past clearing prices, mileageratios, and event probabilities to determine the revenue generationpotential of selling stored energy to resource purchasers 441 or energygrid 442. For the PBDR programs, asset allocator 402 may use predictionsof ambient conditions, facility thermal loads, and thermodynamic modelsof installed equipment to estimate the resource consumption of subplants420. Asset allocator 402 may use predictions of the resource consumptionto monetize the costs of running the equipment.

Asset allocator 402 may automatically determine (e.g., without humanintervention) a combination of PBDR and/or IBDR programs in which toparticipate over the optimization horizon in order to maximize economicvalue. For example, asset allocator 402 may consider the revenuegeneration potential of IBDR programs, the cost reduction potential ofPBDR programs, and the equipment maintenance/replacement costs thatwould result from participating in various combinations of the IBDRprograms and PBDR programs. Asset allocator 402 may weigh the benefitsof participation against the costs of participation to determine anoptimal combination of programs in which to participate. Advantageously,this allows asset allocator 402 to determine an optimal set of controldecisions that maximize the overall value of operating asset allocationsystem 400.

In some embodiments, asset allocator 402 optimizes the objectivefunction subject to the following constraint, which guarantees thebalance between resources purchased, produced, discharged, consumed, andrequested over the optimization horizon:

${{{\sum\limits_{sources}{purchase_{{resource},{time}}}} +  {\sum\limits_{subplants}{{produces}\left( {x_{{i{nternal}},{time}},x_{{e{xternal}},{time}},v_{{unc{ontroll}ed},{time}}} \right)}} - {\sum\limits_{subplants}{{consumes}\left( {x_{{i{nternal}},{time}},x_{{e{xternal}},{time}},v_{{unc{ontroll}ed},{time}}} \right)}} + {\sum\limits_{{storage}s}{{discharges}_{resource}\left( {x_{{i{nternal}},{t{ime}}},x_{{e{xternal}},{time}}} \right)}} - {\sum\limits_{si{nks}}{requests_{resource}}}} = {0\mspace{31mu} {\forall{resources}}}},{\forall{{time} \in {horizon}}}$

where x_(internal,time) includes internal decision variables (e.g., loadallocated to each component of asset allocation system 400),x_(external,time) includes external decision variables (e.g., condenserwater return temperature or other shared variables across subplants420), and v_(uncontrolled,time) includes uncontrolled variables (e.g.,weather conditions).

The first term in the previous equation represents the total amount ofeach resource (e.g., electricity, water, natural gas, etc.) purchasedfrom each source 410 over the optimization horizon. The second and thirdterms represent the total production and consumption of each resource bysubplants 420 over the optimization horizon. The fourth term representsthe total amount of each resource discharged from storage 430 over theoptimization horizon. Positive values indicate that the resource isdischarged from storage 430, whereas negative values indicate that theresource is charged or stored. The fifth term represents the totalamount of each resource requested by sinks 440 over the optimizationhorizon. Accordingly, this constraint ensures that the total amount ofeach resource purchased, produced, or discharged from storage 430 isequal to the amount of each resource consumed, stored, or provided tosinks 440.

In some embodiments, additional constraints exist on the regions inwhich subplants 420 can operate. Examples of such additional constraintsinclude the acceptable space (i.e., the feasible region) for thedecision variables given the uncontrolled conditions, the maximum amountof a resource that can be purchased from a given source 410, and anynumber of plant-specific constraints that result from the mechanicaldesign of the plant.

Asset allocator 402 may include a variety of features that enable theapplication of asset allocator 402 to nearly any central plant, centralenergy facility, combined heating and cooling facility, or combined heatand power facility. These features include broadly applicabledefinitions for subplants 420, sinks 440, storage 430, and sources 410;multiples of the same type of subplant 420 or sink 440; subplantresource connections that describe which subplants 420 can sendresources to which sinks 440 and at what efficiency; subplant minimumturndown into the asset allocation optimization; treating electricalenergy as any other resource that must be balanced; constraints that canbe commissioned during runtime; different levels of accuracy atdifferent points in the horizon; setpoints (or other decisions) that areshared between multiple subplants included in the decision vector;disjoint subplant operation regions; incentive based electrical energyprograms; and high level airside models. Incorporation of these featuresmay allow asset allocator 402 to support a majority of the centralenergy facilities that will be seen in the future. Additionally, it willbe possible to rapidly adapt to the inclusion of new subplant types.Some of these features are described in greater detail below.

Broadly applicable definitions for subplants 420, sinks 440, storage430, and sources 410 allow each of these components to be described bythe mapping from decision variables to resources consume and resourcesproduced. Resources and other components of system 400 do not need to be“typed,” but rather can be defined generally. The mapping from decisionvariables to resource consumption and production can change based onextrinsic conditions. Asset allocator 420 can solve the optimizationproblem by simply balancing resource use and can be configured to solvein terms of consumed resource 1, consumed resource 2, produced resource1, etc., rather than electricity consumed, water consumed, and chilledwater produced. Such an interface at the high level allows for themappings to be injected into asset allocation system 400 rather thanneeding them hard coded. Of course, “typed” resources and othercomponents of system 400 can still exist in order to generate themapping at run time, based on equipment out of service.

Incorporating multiple subplants 420 or sinks 440 of the same typeallows for modeling the interconnections between subplants 420, sources410, storage 430, and sinks 440. This type of modeling describes whichsubplants 420 can use resource from which sources 410 and whichsubplants 420 can send resources to which sinks 440. This can bevisualized as a resource connection matrix (i.e., a directed graph)between the subplants 420, sources 410, sinks 440, and storage 430.Extending this concept, it is possible to include costs for deliveringthe resource along a connection and also, efficiencies of thetransmission (e.g., amount of energy that makes it to the other side ofthe connection).

In some instances, constraints arise due to mechanical problems after anenergy facility has been built. Accordingly, these constraints are sitespecific and are often not incorporated into the main code for any ofsubplants 420 or the high level problem itself. Commissioned constraintsallow for such constraints to be added without software updates duringthe commissioning phase of the project. Furthermore, if these additionalconstraints are known prior to the plant build, they can be added to thedesign tool run. This would allow the user to determine the cost ofmaking certain design decisions.

Incentive programs often require the reservation of one or more assetsfor a period of time. In traditional systems, these assets are typicallyturned over to alternative control, different than the typical resourceprice based optimization. Advantageously, asset allocator 402 can beconfigured to add revenue to the cost function per amount of resourcereserved. Asset allocator 402 can then make the reserved portion of theresource unavailable for typical price based cost optimization. Forexample, asset allocator 402 can reserve a portion of a battery assetfor frequency response. In this case, the battery can be used to movethe load or shave the peak demand, but can also be reserved toparticipate in the frequency response program.

Central Plant Controller

Referring now to FIG. 5, a block diagram of a central plant controller500 in which asset allocator 402 can be implemented is shown, accordingto an exemplary embodiment. In various embodiments, central plantcontroller 500 can be configured to monitor and control central plant200, asset allocation system 400, and various components thereof (e.g.,sources 410, subplants 420, storage 430, sinks 440, etc.). Central plantcontroller 500 is shown providing control decisions to a buildingmanagement system (BMS) 506. The control decisions provided to BMS 506may include resource purchase amounts for sources 410, setpoints forsubplants 420, and/or charge/discharge rates for storage 430. In otherembodiments, the central plant controller is configured in a planningtool implementation in which an operation of the central plant isplanned over an optimization horizon (e.g., 1 year) for use in planning,operational decision-making, budgeting, planning for purchase of newassets, etc.

In some embodiments, BMS 506 is the same or similar to the BMS describedwith reference to FIG. 1. BMS 506 may be configured to monitorconditions within a controlled building or building zone. For example,BMS 506 may receive input from various sensors (e.g., temperaturesensors, humidity sensors, airflow sensors, voltage sensors, etc.)distributed throughout the building and may report building conditionsto central plant controller 500. Building conditions may include, forexample, a temperature of the building or a zone of the building, apower consumption (e.g., electric load) of the building, a state of oneor more actuators configured to affect a controlled state within thebuilding, or other types of information relating to the controlledbuilding. BMS 506 may operate subplants 420 and storage 430 to affectthe monitored conditions within the building and to serve the thermalenergy loads of the building.

BMS 506 may receive control signals from central plant controller 500specifying on/off states, charge/discharge rates, and/or setpoints forthe subplant equipment. BMS 506 may control the equipment (e.g., viaactuators, power relays, etc.) in accordance with the control signalsprovided by central plant controller 500. For example, BMS 506 mayoperate the equipment using closed loop control to achieve the setpointsspecified by central plant controller 500. In various embodiments, BMS506 may be combined with central plant controller 500 or may be part ofa separate building management system. According to an exemplaryembodiment, BMS 506 is a METASYS® brand building management system, assold by Johnson Controls, Inc.

Central plant controller 500 may monitor the status of the controlledbuilding using information received from BMS 506. Central plantcontroller 500 may be configured to predict the thermal energy loads(e.g., heating loads, cooling loads, etc.) of the building for pluralityof time steps in an optimization horizon (e.g., using weather forecastsfrom a weather service 504). Central plant controller 500 may alsopredict the revenue generation potential of incentive based demandresponse (IBDR) programs using an incentive event history (e.g., pastclearing prices, mileage ratios, event probabilities, etc.) fromincentive programs 502. Central plant controller 500 may generatecontrol decisions that optimize the economic value of operating centralplant 200 over the duration of the optimization horizon subject toconstraints on the optimization process (e.g., energy balanceconstraints, load satisfaction constraints, etc.). The optimizationprocess performed by central plant controller 500 is described ingreater detail below.

In some embodiments, central plant controller 500 is integrated within asingle computer (e.g., one server, one housing, etc.). In various otherexemplary embodiments, central plant controller 500 can be distributedacross multiple servers or computers (e.g., that can exist indistributed locations). In another exemplary embodiment, central plantcontroller 500 may integrated with a smart building manager that managesmultiple building systems and/or combined with BMS 506.

Central plant controller 500 is shown to include a communicationsinterface 536 and a processing circuit 507. Communications interface 536may include wired or wireless interfaces (e.g., jacks, antennas,transmitters, receivers, transceivers, wire terminals, etc.) forconducting data communications with various systems, devices, ornetworks. For example, communications interface 536 may include anEthernet card and port for sending and receiving data via anEthernet-based communications network and/or a WiFi transceiver forcommunicating via a wireless communications network. Communicationsinterface 536 may be configured to communicate via local area networksor wide area networks (e.g., the Internet, a building WAN, etc.) and mayuse a variety of communications protocols (e.g., BACnet, IP, LON, etc.).

Communications interface 536 may be a network interface configured tofacilitate electronic data communications between central plantcontroller 500 and various external systems or devices (e.g., BMS 506,subplants 420, storage 430, sources 410, etc.). For example, centralplant controller 500 may receive information from BMS 506 indicating oneor more measured states of the controlled building (e.g., temperature,humidity, electric loads, etc.) and one or more states of subplants 420and/or storage 430 (e.g., equipment status, power consumption, equipmentavailability, etc.). Communications interface 536 may receive inputsfrom BMS 506, subplants 420, and/or storage 430 and may provideoperating parameters (e.g., on/off decisions, setpoints, etc.) tosubplants 420 and storage 430 via BMS 506. The operating parameters maycause subplants 420 and storage 430 to activate, deactivate, or adjust asetpoint for various devices thereof.

Still referring to FIG. 5, processing circuit 507 is shown to include aprocessor 508 and memory 510. Processor 508 may be a general purpose orspecific purpose processor, an application specific integrated circuit(ASIC), one or more field programmable gate arrays (FPGAs), a group ofprocessing components, or other suitable processing components.Processor 508 may be configured to execute computer code or instructionsstored in memory 510 or received from other computer readable media(e.g., CDROM, network storage, a remote server, etc.).

Memory 510 may include one or more devices (e.g., memory units, memorydevices, storage devices, etc.) for storing data and/or computer codefor completing and/or facilitating the various processes described inthe present disclosure. Memory 510 may include random access memory(RAM), read-only memory (ROM), hard drive storage, temporary storage,non-volatile memory, flash memory, optical memory, or any other suitablememory for storing software objects and/or computer instructions. Memory510 may include database components, object code components, scriptcomponents, or any other type of information structure for supportingthe various activities and information structures described in thepresent disclosure. Memory 510 may be communicably connected toprocessor 508 via processing circuit 507 and may include computer codefor executing (e.g., by processor 508) one or more processes describedherein.

Memory 510 is shown to include a building status monitor 524. Centralplant controller 500 may receive data regarding the overall building orbuilding space to be heated or cooled by system 400 via building statusmonitor 524. In an exemplary embodiment, building status monitor 524 mayinclude a graphical user interface component configured to providegraphical user interfaces to a user for selecting building requirements(e.g., overall temperature parameters, selecting schedules for thebuilding, selecting different temperature levels for different buildingzones, etc.).

Central plant controller 500 may determine on/off configurations andoperating setpoints to satisfy the building requirements received frombuilding status monitor 524. In some embodiments, building statusmonitor 524 receives, collects, stores, and/or transmits cooling loadrequirements, building temperature setpoints, occupancy data, weatherdata, energy data, schedule data, and other building parameters. In someembodiments, building status monitor 524 stores data regarding energycosts, such as pricing information available from sources 410 (energycharge, demand charge, etc.).

Still referring to FIG. 5, memory 510 is shown to include a load/ratepredictor 522. Load/rate predictor 522 may be configured to predict thethermal energy loads (

) of the building or campus for each time step k (e.g., k=1 . . . n) ofan optimization horizon. Load/rate predictor 522 is shown receivingweather forecasts from a weather service 504. In some embodiments,load/rate predictor 522 predicts the thermal energy loads

as a function of the weather forecasts. In some embodiments, load/ratepredictor 522 uses feedback from BMS 506 to predict loads

. Feedback from BMS 506 may include various types of sensory inputs(e.g., temperature, flow, humidity, enthalpy, etc.) or other datarelating to the controlled building (e.g., inputs from a HVAC system, alighting control system, a security system, a water system, etc.).

In some embodiments, load/rate predictor 522 receives a measuredelectric load and/or previous measured load data from BMS 506 (e.g., viabuilding status monitor 524). Load/rate predictor 522 may predict loads

as a function of a given weather forecast ({circumflex over (ϕ)}_(w)), aday type (day), the time of day (t), and previous measured load data(Y_(k-1)). Such a relationship is expressed in the following equation:

=f({circumflex over (ϕ)}_(w),day,t|Y _(k-1))

In some embodiments, load/rate predictor 522 uses a deterministic plusstochastic model trained from historical load data to predict loads

. Load/rate predictor 522 may use any of a variety of prediction methodsto predict loads

(e.g., linear regression for the deterministic portion and an AR modelfor the stochastic portion). Load/rate predictor 522 may predict one ormore different types of loads for the building or campus. For example,load/rate predictor 522 may predict a hot water load

and a cold water load

for each time step k within the prediction window. In some embodiments,load/rate predictor 522 makes load/rate predictions using the techniquesdescribed in U.S. patent application Ser. No. 14/717,593.

Load/rate predictor 522 is shown receiving utility rates from sources410. Utility rates may indicate a cost or price per unit of a resource(e.g., electricity, natural gas, water, etc.) provided by sources 410 ateach time step k in the prediction window. In some embodiments, theutility rates are time-variable rates. For example, the price ofelectricity may be higher at certain times of day or days of the week(e.g., during high demand periods) and lower at other times of day ordays of the week (e.g., during low demand periods). The utility ratesmay define various time periods and a cost per unit of a resource duringeach time period. Utility rates may be actual rates received fromsources 410 or predicted utility rates estimated by load/rate predictor522.

In some embodiments, the utility rates include demand charges for one ormore resources provided by sources 410. A demand charge may define aseparate cost imposed by sources 410 based on the maximum usage of aparticular resource (e.g., maximum energy consumption) during a demandcharge period. The utility rates may define various demand chargeperiods and one or more demand charges associated with each demandcharge period. In some instances, demand charge periods may overlappartially or completely with each other and/or with the predictionwindow. Advantageously, demand response optimizer 530 may be configuredto account for demand charges in the high level optimization processperformed by asset allocator 402. Sources 410 may be defined bytime-variable (e.g., hourly) prices, a maximum service level (e.g., amaximum rate of consumption allowed by the physical infrastructure or bycontract) and, in the case of electricity, a demand charge or a chargefor the peak rate of consumption within a certain period. Load/ratepredictor 522 may store the predicted loads

and the utility rates in memory 510 and/or provide the predicted loads

and the utility rates to demand response optimizer 530.

Still referring to FIG. 5, memory 510 is shown to include an incentiveestimator 520. Incentive estimator 520 may be configured to estimate therevenue generation potential of participating in various incentive-baseddemand response (IBDR) programs. In some embodiments, incentiveestimator 520 receives an incentive event history from incentiveprograms 502. The incentive event history may include a history of pastIBDR events from incentive programs 502. An IBDR event may include aninvitation from incentive programs 502 to participate in an IBDR programin exchange for a monetary incentive. The incentive event history mayindicate the times at which the past IBDR events occurred and attributesdescribing the IBDR events (e.g., clearing prices, mileage ratios,participation requirements, etc.). Incentive estimator 520 may use theincentive event history to estimate IBDR event probabilities during theoptimization horizon.

Incentive estimator 520 is shown providing incentive predictions todemand response optimizer 530. The incentive predictions may include theestimated IBDR probabilities, estimated participation requirements, anestimated amount of revenue from participating in the estimated IBDRevents, and/or any other attributes of the predicted IBDR events. Demandresponse optimizer 530 may use the incentive predictions along with thepredicted loads

and utility rates from load/rate predictor 522 to determine an optimalset of control decisions for each time step within the optimizationhorizon.

Still referring to FIG. 5, memory 510 is shown to include a demandresponse optimizer 530. Demand response optimizer 530 may perform acascaded optimization process to optimize the performance of assetallocation system 400. For example, demand response optimizer 530 isshown to include asset allocator 402 and a low level optimizer 534.Asset allocator 402 may control an outer (e.g., subplant level) loop ofthe cascaded optimization. Asset allocator 402 may determine an optimalset of control decisions for each time step in the prediction window inorder to optimize (e.g., maximize) the value of operating assetallocation system 400. Control decisions made by asset allocator 402 mayinclude, for example, load setpoints for each of subplants 420,charge/discharge rates for each of storage 430, resource purchaseamounts for each type of resource purchased from sources 410, and/or anamount of each resource sold to energy purchasers 504. In other words,the control decisions may define resource allocation at each time step.The control decisions made by asset allocator 402 are based on thestatistical estimates of incentive event probabilities and revenuegeneration potential for various IBDR events as well as the load andrate predictions.

Low level optimizer 534 may control an inner (e.g., equipment level)loop of the cascaded optimization. Low level optimizer 534 may determinehow to best run each subplant at the load setpoint determined by assetallocator 402. For example, low level optimizer 534 may determine on/offstates and/or operating setpoints for various devices of the subplantequipment in order to optimize (e.g., minimize) the energy consumptionof each subplant while meeting the resource allocation setpoint for thesubplant. In some embodiments, low level optimizer 534 receives actualincentive events from incentive programs 502. Low level optimizer 534may determine whether to participate in the incentive events based onthe resource allocation set by asset allocator 402. For example, ifinsufficient resources have been allocated to a particular IBDR programby asset allocator 402 or if the allocated resources have already beenused, low level optimizer 534 may determine that asset allocation system400 will not participate in the IBDR program and may ignore the IBDRevent. However, if the required resources have been allocated to theIBDR program and are available in storage 430, low level optimizer 534may determine that system 400 will participate in the IBDR program inresponse to the IBDR event. The cascaded optimization process performedby demand response optimizer 530 is described in greater detail in U.S.patent application Ser. No. 15/247,885.

In some embodiments, low level optimizer 534 generates and providessubplant curves to asset allocator 402. Each subplant curve may indicatean amount of resource consumption by a particular subplant (e.g.,electricity use measured in kW, water use measured in L/s, etc.) as afunction of the subplant load. In some embodiments, low level optimizer534 generates the subplant curves by running the low level optimizationprocess for various combinations of subplant loads and weatherconditions to generate multiple data points. Low level optimizer 534 mayfit a curve to the data points to generate the subplant curves. In otherembodiments, low level optimizer 534 provides the data points assetallocator 402 and asset allocator 402 generates the subplant curvesusing the data points. Asset allocator 402 may store the subplant curvesin memory for use in the high level (i.e., asset allocation)optimization process.

In some embodiments, the subplant curves are generated by combiningefficiency curves for individual devices of a subplant. A deviceefficiency curve may indicate the amount of resource consumption by thedevice as a function of load. The device efficiency curves may beprovided by a device manufacturer or generated using experimental data.In some embodiments, the device efficiency curves are based on aninitial efficiency curve provided by a device manufacturer and updatedusing experimental data. The device efficiency curves may be stored inequipment models 518. For some devices, the device efficiency curves mayindicate that resource consumption is a U-shaped function of load.Accordingly, when multiple device efficiency curves are combined into asubplant curve for the entire subplant, the resultant subplant curve maybe a wavy curve. The waves are caused by a single device loading upbefore it is more efficient to turn on another device to satisfy thesubplant load.

Still referring to FIG. 5, memory 510 is shown to include a subplantcontrol module 528. Subplant control module 528 may store historicaldata regarding past operating statuses, past operating setpoints, andinstructions for calculating and/or implementing control parameters forsubplants 420 and storage 430. Subplant control module 528 may alsoreceive, store, and/or transmit data regarding the conditions ofindividual devices of the subplant equipment, such as operatingefficiency, equipment degradation, a date since last service, a lifespanparameter, a condition grade, or other device-specific data. Subplantcontrol module 528 may receive data from subplants 420, storage 430,and/or BMS 506 via communications interface 536. Subplant control module528 may also receive and store on/off statuses and operating setpointsfrom low level optimizer 534.

Data and processing results from demand response optimizer 530, subplantcontrol module 528, or other modules of central plant controller 500 maybe accessed by (or pushed to) monitoring and reporting applications 526.Monitoring and reporting applications 526 may be configured to generatereal time “system health” dashboards that can be viewed and navigated bya user (e.g., a system engineer). For example, monitoring and reportingapplications 526 may include a web-based monitoring application withseveral graphical user interface (GUI) elements (e.g., widgets,dashboard controls, windows, etc.) for displaying key performanceindicators (KPI) or other information to users of a GUI. In addition,the GUI elements may summarize relative energy use and intensity acrossenergy storage systems in different buildings (real or modeled),different campuses, or the like. Other GUI elements or reports may begenerated and shown based on available data that allow users to assessperformance across one or more energy storage systems from one screen.The user interface or report (or underlying data engine) may beconfigured to aggregate and categorize operating conditions by building,building type, equipment type, and the like. The GUI elements mayinclude charts or histograms that allow the user to visually analyze theoperating parameters and power consumption for the devices of the energystorage system.

Still referring to FIG. 5, central plant controller 500 may include oneor more GUI servers, web services 512, or GUI engines 514 to supportmonitoring and reporting applications 526. In various embodiments,applications 526, web services 512, and GUI engine 514 may be providedas separate components outside of central plant controller 500 (e.g., aspart of a smart building manager). Central plant controller 500 may beconfigured to maintain detailed historical databases (e.g., relationaldatabases, XML databases, etc.) of relevant data and includes computercode modules that continuously, frequently, or infrequently query,aggregate, transform, search, or otherwise process the data maintainedin the detailed databases. Central plant controller 500 may beconfigured to provide the results of any such processing to otherdatabases, tables, XML files, or other data structures for furtherquerying, calculation, or access by, for example, external monitoringand reporting applications.

Central plant controller 500 is shown to include configuration tools516. Configuration tools 516 can allow a user to define (e.g., viagraphical user interfaces, via prompt-driven “wizards,” etc.) howcentral plant controller 500 should react to changing conditions in theenergy storage subsystems. In an exemplary embodiment, configurationtools 516 allow a user to build and store condition-response scenariosthat can cross multiple energy storage system devices, multiple buildingsystems, and multiple enterprise control applications (e.g., work ordermanagement system applications, entity resource planning applications,etc.). For example, configuration tools 516 can provide the user withthe ability to combine data (e.g., from subsystems, from eventhistories) using a variety of conditional logic. In varying exemplaryembodiments, the conditional logic can range from simple logicaloperators between conditions (e.g., AND, OR, XOR, etc.) to pseudo-codeconstructs or complex programming language functions (allowing for morecomplex interactions, conditional statements, loops, etc.).Configuration tools 516 can present user interfaces for building suchconditional logic. The user interfaces may allow users to definepolicies and responses graphically. In some embodiments, the userinterfaces may allow a user to select a pre-stored or pre-constructedpolicy and adapt it or enable it for use with their system.

Asset Allocator

Referring now to FIG. 6, a block diagram illustrating asset allocator402 in greater detail is shown, according to an exemplary embodiment.Asset allocator 402 may be configured to control the distribution,production, storage, and usage of resources in a central plant. Assetallocator 402 can be configured to generate a high-level optimizationproblem, generate constraints for the optimization problem, and solvethe optimization problem subject to the constraints. Based on theresults of the optimization process, asset allocator 402 may dispatchall campus energy assets in order to meet the requested heating,cooling, and electrical loads of the campus for each time step within anoptimization horizon or optimization horizon.

In some embodiments, asset allocator 402 can be configured to minimizethe economic cost of operating a central plant over the duration of theoptimization horizon, as described above. The economic cost may bedefined by a cost function J(x) that expresses economic cost as afunction of the control decisions made by asset allocator 402. The costfunction J(x) may account for the cost of resources purchased fromsources 410, as well as the revenue generated by selling resources toresource purchasers 441 or energy grid 442 or participating in incentiveprograms. In some embodiments, asset allocator 402 may be configured tominimize the total amount of each resource obtained from sources 410over the duration of the optimization horizon, regardless of cost orprice, to minimize the resource consumption of asset allocation system400.

In some embodiments, asset allocator 402 performs an optimizationprocess to determine an optimal set of control decisions for each timestep within an optimization horizon. The control decisions may include,for example, an optimal amount of each resource to purchase from sources410, an optimal amount of each resource to produce or convert usingsubplants 420, an optimal amount of each resource to store or removefrom storage 430, an optimal amount of each resource to sell toresources purchasers 441 or energy grid 440, and/or an optimal amount ofeach resource to provide to other sinks 440. In some embodiments, assetallocator 402 is configured to optimally dispatch all campus energyassets in order to meet the requested heating, cooling, and electricalloads of the campus for each time step within the optimization horizon.

Throughout this disclosure, asset allocator 402 is described as activelyidentifying or defining various items (e.g., sources 410, subplants 420,storage 430, sinks 440, operational domains, etc.). However, it shouldbe understood that asset allocator 402 can also, or alternatively,receive such items as inputs. For example, the existence of such itemscan be defined by a user (e.g., via a user interface) or any other datasource (e.g., another algorithm, an external system or process, etc.).Asset allocator 402 can be configured to identify which of these itemshave been defined or identified and can generate an appropriateobjective function and optimization constraints, based on the existenceof these items. It should be understood that the acts of identifying ordefining these items can include asset allocator 402 identifying,detecting, receiving, or otherwise obtaining a predefined item an input.

Still referring to FIG. 6, asset allocator 402 is shown to include anoptimization problem constructor 602. Optimization problem constructor602 can be configured to construct the high level (i.e., assetallocation) optimization problem solved by asset allocator 402. In someembodiments, the high level optimization problem includes one or more ofthe elements of asset allocation system 400. For example, theoptimization problem can include sources 410, subplants 420, storage430, and sinks 440, as described with reference to FIG. 4. Theoptimization problem generated by optimization problem constructor 602can be considered a finite-horizon optimal control problem. Theoptimization problem may take the form arg_(x) min F(x), where F(x) isan objective function.

In some embodiments, F(x) may be defined as the cost function J(x) asdefined above. In some embodiments, F(x) may be an objective functionthat quantifies energy/resource consumption rather than financial cost,such as by summing a total amount of each resource obtained from source410. Optimization problem constructor 602 can be configured to generatethe objective function and apply the objective function to theoptimization problem. Optimization problem constructor 602 may take intoaccount all variables which may impact the objective function, such asthe load capacity of subplants 420 or the storage capacity of storage430, for example.

Still referring to FIG. 6, asset allocator 402 is shown to includeconstraints generator 604. Constraints generator 604 may generateconstraints for the high level optimization problem, including resourcebalance constraints (e.g., hot water balance, chilled water balance,electricity balance, etc.), operational domain constraints for each ofsubplants 420, state of charge (SOC) and storage capacity constraintsfor each of storage 430, decision variable constraints (e.g., subplantcapacity constraints, charge and discharge of storage constraints, andstorage capacity constraints), demand/peak usage constraints, auxiliaryconstraints, and any site specific or commissioned constraints.Operational domain constraints may be generalized versions of thesubplant curves, as described in U.S. patent application Ser. No.15/473,496 filed Mar. 29, 2017, which is incorporated by referenceherein in its entirety.

In some embodiments, constraints generator 604 may generate a set ofoverride constraints based on a user input specifying an amount of aresource to be produced by a selected subplant. Override constraints maybe generated based on a user input. For example, a user may selectelectricity subplant 425 and specify an amount of electricity to beproduced by the subplant by entering a load (e.g., a percentage ofmaximum subplant load) for electricity subplant 425 to produce.Generally, override constraints may include hard constraints and/or softconstraints, described below.

In some embodiments, hard constraints may be may be defined asS_(subplant)produces=O_(subplant), where S_(subplant)produces is theamount of a resource produced by a subplant and O_(subplant) is theoverride amount. In other embodiments, hard constraints may be may bedefined as S_(subplant)produces−O_(subplant)≤e_(subplant) andO_(subplant)−S_(subplant)produces≤e_(subplant), where e_(subplant) is anallowed error between the amount of the resource produced by a subplantand the override value commanded by the user. Another way to write thisconstraint is−e_(subplant)≤S_(subplant)produces−O_(subplant)≤e_(subplant). In thecase of hard constraints, the allowed error e_(subplant) may be set to afixed value (e.g., e_(subplant)=25) such that the difference between thesubplant production S_(subplant)produces and the override amountO_(subplant) is kept within a range between −e_(subplant) ande_(subplant), regardless of whether S_(subplant)produces is greater thanO_(subplant) or vice versa. The fixed value of the allowed errore_(subplant) may depend on the particular type of resource or subplantto which the constraint applies and, in some embodiments, can bespecified by a user along with the override amount O_(subplant). Ineither case, each variable of the constraints may be treated as avector, such that each variable can contain multiple values. Forexample, O_(subplant) may be defined as [O_(subplant) ₁ , O_(subplant) ₂, . . . , O_(subplant) _(h) ], where h is the total number of time stepsof an optimization horizon. In some cases, the user may wish to overridethe subplant loads for only a subset of the time steps in theoptimization horizon, in which case the variable O_(subplant) would be avector that specifies subplant load values for only a subset of timesteps. Any values that are not specified by the user may be treated asfree variables to be in the optimization process.

In some embodiments, soft constraints may be may be defined as a penaltyterm added to the objective function along with correspondingoptimization constraints that apply to the penalty term. Softconstraints allow the amount of a resource produced by a subplant,S_(subplant)produces, to take a larger range of values, but penalize adifference between the S_(subplant)produces value and the override valueO_(subplant). For example, a soft constraint may be added to the costfunction J(x) such that:

${J(x)} = {{\sum\limits_{sources}{\sum\limits_{{horizo}n}{{cost}\left( {{{pur}chase_{{resource},{time}}},{time}} \right)}}} - {\sum\limits_{incentives}{\sum\limits_{{horizo}n}{{revenue}({ReservationAmount})}}} + {p*d_{subplant}}}$

where d_(subplant) is a slack variable representing a difference betweenS_(subplant)produces and O_(subplant), and p is a penalty weight that ismultiplied by d_(subplant). The slack variable d_(subplant) can beconstrained by adding the optimization constraintsS_(subplant)produces−O_(subplant)≤d_(subplant) andO_(subplant)−S_(subplant)produces≤d_(subplant) to the optimizationproblem such that d_(subplant) will be greater than or equal to thedifference between S_(subplant)produces and subplant regardless ofwhether S_(subplant)produces is greater than O_(subplant) or vice versa.These two constraints are functionally equivalent to a single constraint|S_(subplant)produces−O_(subplant)|≤d_(subplant) that requiresd_(subplant) to be greater than or equal to the absolute value of thedifference S_(subplant)produces−O_(subplant). However, replacing thisabsolute value constraint with the pair of constraintsS_(subplant)produces−O_(subplant)≤d_(subplant) andO_(subplant)−S_(subplant)produces≤d_(subplant) advantageously allows forall of the constraints to be linear, which reduces computation time.

Still referring to FIG. 6, asset allocator 402 is shown to includeoptimization problem analyzer 606. Optimization problem analyzer 606 maybe configured to solve the high level optimization problem generated byoptimization problem constructor 602. In other words, optimizationproblem analyzer 606 may be configured to perform an optimization on anobjective function. For example, optimization problem analyzer 606 mayminimize the value F(x), as required by the optimization problemarg_(x)min F(x). Optimization problem analyzer 606 may also beconfigured to perform the optimization on the objective function subjectto one or more of the constraints described above. In normal operation,optimization problem analyzer 606 does not subject the optimization ofthe object function to an override constraint. Override constraints areonly applied by optimization problem analyzer 606 in response to a userinput of an override value.

Optimization problem analyzer 606 may determine an amount of eachresource to be purchased, produced, discharged, consumed, or requestedby each element of the central plant (e.g., each subplant), based on theresults of the optimization problem. More generally, optimizationproblem analyzer 606 determines a set of control decisions for eachelement of the central plant. Control decisions may include, forexample, an optimal amount of each resource to purchase from sources410, an optimal amount of each resource to produce or convert usingsubplants 420, an optimal amount of each resource to store or removefrom storage 430, an optimal amount of each resource to sell toresources purchasers 441 or energy grid 440, and/or an optimal amount ofeach resource to provide to other sinks 440. In some embodiments, thecontrol decisions include an optimal amount of each input resource andoutput resource for each of subplants 420.

In some embodiments, optimization problem analyzer 606 determines avector of load values for each subplant, where each value of the vectorof load values corresponds to a time step. For example, optimizationproblem analyzer 606 may determine load setpoints for each of subplants420, charge/discharge rates for each of storage 430, resource purchaseamounts for each type of resource purchased from sources 410, and/or anamount of each resource sold to energy purchasers 504.

Still referring to FIG. 6, asset allocator 402 is shown to include assetcontroller 608. Asset controller 608 may be configured to controlelements of asset allocation system 400 based on the set of controldecisions determined by optimization problem analyzer 606. Assetcontroller 608 may command load setpoints for each of subplants 420,charge/discharge rates for each of storage 430, and/or resource purchaseamounts for each type of resource purchased from sources 410. Assetcontroller 608 may generally operate at a subplant level, sendingcontrol signals to sources 410, subplants 420, storage 430, and/or sinks440, while not directly controlling building equipment (e.g., individualsubplants).

Still referring to FIG. 6, asset allocator 402 is shown to includeelement models 630. Element models 630 may store definitions and/ormodels for various elements of the high level optimization problem. Forexample, element models 630 are shown to include source models 610,source models 612, subplant models 614, storage models 616, and elementlinks 618. In some embodiments, element models 630 include data objectsthat define various attributes or properties of sinks 440, sources 410,subplants 420, and storage 430 (e.g., using object-orientedprogramming).

For example, source models 612 may define the type of resource providedby each of sources 410, a cost of each resource, demand chargesassociated with the consumption of the resource, a maximum rate at whichthe resource can be purchased from each of sources 410, and otherattributes of sources 410. Similarly, subplant models 614 may define theinput resources of each subplant 420, the output resources of eachsubplant 420, relationships between the input and output variables ofeach subplant 420 (i.e., the operational domain of each subplant 420),and optimization constraints associated with each of subplants 420. Eachof element models 630 are described in greater detail below.

Element models 630 are shown to include source models 610. Source models610 may store models for each of sinks 440. As described above, sinks440 may include resource consumers or requested loads. Some examples arethe campus thermal loads and campus electricity usage. The predictedconsumption of a sink 440 over the optimization horizon can be suppliedas an input to asset allocator 402 and/or computed by load/ratepredictor 522. Source models 610 may store the predicted consumptionover the optimization horizon for each of sinks 440. Source models 610may also store any unmet/overmet load for each of sinks 440, carryoverfrom the previous time steps, and any incentives earned by supplyingeach of sinks 440 (e.g., for sinks such as an energy purchasers or anenergy grid).

Carryover can be defined as the amount of unmet or overmet load for aparticular resource from the previous time step. In some embodiments,asset allocator 402 determines the carryover by adding the entire unmetload for a particular resource in one time step to the requested loadfor the resource at the next time step. However, calculating thecarryover in this manner may not always be appropriate since thecarryover may grow over time. As an example, consider an unmet chilledwater load. If there are several time steps where the chilled water loadis not met, the buildings supplied by the load will heat up. Due to thisincrease in building temperature, the amount of chilled water loadrequired to decrease the building temperature to the set-point is not alinearly increasing function of the sum of the unmet load over the pasttime steps because the building temperature will begin approaching theambient temperature.

Still referring to FIG. 6, element models 630 are shown to includesource models 612. Source models 612 may store models for each ofsources 410. As described above, sources 410 may include utilities ormarkets where resources may be purchased. Source models 612 may store aprice per unit of a resource purchased from each of sources 410 (e.g.,$/kWh of electricity, $/liter of water, etc.). This cost can be includedas a direct cost associated with resource usage in the cost function. Insome embodiments, source models 612 store costs associated with demandcharges and demand constraints, incentive programs (e.g., frequencyresponse and economic demand response) and/or sell back programs for oneor more of sources 410.

Referring again to FIG. 6, element models 630 are shown to includesubplant models 614. Subplant models 614 may store models for each ofsubplants 420. As discussed above, subplants 420 are the main assets ofa central plant. Subplants 420 can be configured to convert resourcetypes, making it possible to balance requested loads from the buildingor campus using resources purchased from sources 410. This generaldefinition allows for a diverse set of central plant configurations andequipment types as well as varying degrees of subplant modeling fidelityand resolution.

In some embodiments, subplant models 614 identify each of subplants 420as well as the optimization variables associated with each subplant. Theoptimization variables of a subplant can include the resources consumed,the resources produced, intrinsic variables, and extrinsic variables.Intrinsic variables may be internal to the optimization formulation andcan include any auxiliary variables used to formulate the optimizationproblem. Extrinsic variables may be variables that are shared amongsubplants (e.g., condenser water temperature).

In some embodiments, subplant models 614 describe the relationshipsbetween the optimization variables of each subplant. For example,subplant models 614 can include subplant curves that define the outputresource production of a subplant as a function of one or more inputresources provided to the subplant.

In some embodiments, subplant models 614 store the input data used togenerate the subplant constraints. Such input data may include sampleddata points of the high level subplant curve/operational domain. Forexample, for chiller subplant 422, this data may include several pointssampled from the subplant curve 1300 (shown in FIG. 13). Whenimplemented as part of an online operational tool (shown in FIG. 7), thehigh level subplant operational domain can be sampled by querying lowlevel optimizer 634 at several requested production amounts. Whenimplemented as part of an offline planning tool (shown in FIG. 8), thesampled data may be user-specified efficiency and capacity data.

Still referring to FIG. 6, element models 630 are shown to includestorage models 616. Storage models 616 may store models for each ofstorage 430. Storage models 616 can define the types of resources storedby each of storage 430, as well as storage constraints that limit thestate-of-charge (e.g., maximum charge level) and/or the rates at whicheach storage 430 can be charged or discharged.

Still referring to FIG. 6, element models 630 are shown to includeelement links 618. In some embodiments, element links 618 define theconnections between sources 410, subplants 420, storage 430, and sinks440. These links 940 are shown as lines connecting various elements inplant resource diagram 500. For example, element links 618 may definewhich of sources 410 provide resources to each of subplants 420, whichsubplants 420 are connected to which storage 430, and which subplants420 and/or storage 430 provide resources to each of sinks 440. Elementlinks 618 may contain the data and methods needed to create and solve aninstance of the high level optimization problem.

In some embodiments, element links 618 link sources 410, subplants 420,storage 430, and sinks 440 (i.e., the high level problem elements) usinga netlist of connections between high level problem elements. Theinformation provided by element links 618 may allow multiple subplants420, storage 430, sinks 440, and sources of the same type to be defined.Rather than assuming that all elements contribute to and draw from acommon pool of each resource, element links 618 can be used to specifythe particular connections between elements. Accordingly, multipleresources of the same type can be defined such that a first subset ofsubplants 420 produce a first resource of a given type (e.g., ChilledWater A), whereas a second subset of subplants 420 produce a secondresource of the same type (e.g., Chilled Water B). Advantageously,element links 618 can be used to build constraints that reflect theactual physical connections between equipment in a central plant.

Asset Allocation Override

Referring now to FIG. 7, a flow diagram illustrates optimization process700 which optimizes an objective function subject to a user input of anoverride value of one or more resources produced by one or moresubplants (e.g., subplants 420 of asset allocation system 400),according to some embodiments. Optimization process 700 may be performedby asset allocator 402 as previously disclosed. In some embodiments, auser may override the recommended heating, cooling, electricity, orenergy load of a subplant (e.g., one of subplants 420) by entering anoverride load value (i.e., input override) that more closely suits theuser's desired subplant load. For example, a user may decide that afirst electricity subplant (e.g., electricity subplant 425) shouldproduce more electricity than recommended by asset allocator 402, inwhich case the user may enter a new load setpoint, defining how muchelectricity that electricity subplant 425 should produce. Recommendedsubplant loads may be generated by asset allocator 402 by performing anoptimization of an objective function without override constraints, asdefined above. Asset allocator 402 generally performs an optimization onthe objective function subject to a number of constraints, as definedbelow.

At step 702, an objective function is obtained. In some embodiments, theobjective function may be a cost function J(x), defined as:

${J(x)} = {{\sum\limits_{sources}{\sum\limits_{{horizo}n}{{cost}\left( {{{purch}ase_{{resource},{time}}},{time}} \right)}}} - {\sum\limits_{incentives}{\sum\limits_{{horizo}n}{{revenue}({ReservationAmount})}}}}$

where first term of J(x) represents the total cost of all resourcespurchased by a central plant over an optimization horizon. Resources caninclude, for example, water, electricity, natural gas, or other types ofresources purchased from a utility or other source (e.g., one of sources410). The second term of J(x) represents the total revenue generated byparticipating in incentive programs (e.g., IBDR programs) over theoptimization horizon. The revenue may be based on the amount of powerreserved for participating in the incentive programs. Accordingly, thetotal cost function represents the total cost of resources purchasedminus any revenue generated from participating in incentive programs. Insome embodiments, the objective function quantifies energy/resourceconsumption rather than financial cost by summing a total amount of eachresource obtained from sources 410 over the duration of the optimizationhorizon, regardless of cost or price.

At step 704, a user input is received that selects a subplant andspecifies an amount of a resource to be produced by the selectedsubplant. A user may select a subplant and choose to modify therecommended subplant load (i.e., input a load override) at one or moretime steps over a time horizon. The user input of a subplant loadoverride may be received from a number of sources such as a clientdevice 368 or configuration tools 516, for example. In some embodiments,the user may select multiple subplants and input a unique load overridefor each subplant. For example, one of sinks 440 (e.g., cold water load444) may request an amount, X₀, of a first resource (e.g., cold water).The asset allocator 402 may dispatch a first chiller subplant, S₁ (e.g.,chiller subplant 422) to produce the requested amount, X₀, of coldwater, while a second chiller subplant, S₂ may not be dispatched toproduce chilled water. A user may choose to override one or more of therecommended subplants loads, for example by specifying that the secondchiller subplant S₂ may produce an amount X₂ of water. An amount of coldwater X₁ provided by the first chiller subplant S₁ may then be updatedper the following steps of process 700, such that X₁+X₂=X₀.

At step 706, an override constraint is generated based on the user inputof a load override. In some embodiments, multiple override constraintsare generated, such as when the user selects multiple subplants andinputs a unique load override for each subplant. Override constraintsmay be defined as hard constraints or soft constraints, depending on theapplication and on user preferences. Override constraints are generatedbased on the load override entered at step 704.

In some embodiments, hard constraints may be may be defined asS_(subplant)produces=O_(subplant), where S_(subplant)produces is theamount of a resource produced by a subplant and O_(subplant) is theoverride amount. In other embodiments, hard constraints may be may bedefined as S_(subplant)produces−O_(subplant)≤e_(subplant) andO_(subplant)−S_(subplant)produces≤e_(subplant), where e_(subplant) is anallowed error between the amount of the resource produced by a subplantand the override value commanded by the user. Another way to write thisconstraint is−e_(subplant)≤S_(subplant)produces−O_(subplant)≤e_(subplant). In thecase of hard constraints, the allowed error e_(subplant) may be set to afixed value (e.g., e_(subplant)=25) such that the difference between thesubplant production S_(subplant)produces and the override amountO_(subplant) is kept within a range between −e_(subplant) ande_(subplant), regardless of whether S_(subplant)produces is greater thanO_(subplant) or vice versa. The fixed value of the allowed errore_(subplant) may depend on the particular type of resource or subplantto which the constraint applies and, in some embodiments, can bespecified by a user along with the override amount O_(subplant). Ineither case, each variable of the constraints may be treated as avector, such that each variable can contain multiple values. Forexample, O_(subplant) may be defined as [O_(subplant) ₁ , O_(subplant) ₂, . . . , O_(subplant) _(h) ], where h is the total number of time stepsof an optimization horizon. In some cases, the user may wish to overridethe subplant loads for only a subset of the time steps in theoptimization horizon, in which case the variable O_(subplant) would be avector that specifies subplant load values for only a subset of timesteps. Any values that are not specified by the user may be treated asfree variables to be in the optimization process.

In some embodiments, soft constraints may be may be defined as a penaltyterm added to the objective function along with correspondingoptimization constraints that apply to the penalty term. Softconstraints allow the amount of a resource produced by a subplant,S_(subplant)produces, to take a larger range of values, but penalize adifference between the S_(subplant)produces value and the override valueO_(subplant). For example, a soft constraint may be added to the costfunction J(x) such that:

${J(x)} = {{\sum\limits_{sources}{\sum\limits_{{horizo}n}{{cost}\left( {{{purchas}e_{{resource},{time}}},{time}} \right)}}} - {\sum\limits_{incentives}{\sum\limits_{{horizo}n}{reven{{ue}({ReservationAmount})}}}} + {p*d_{subplant}}}$

where d_(subplant) is a slack variable representing a difference betweenS_(subplant)produces and O_(subplant), and p is a penalty weight that ismultiplied by d_(subplant). The slack variable d_(subplant) can beconstrained by adding the optimization constraintsS_(subplant)produces−O_(subplant)≤d_(subplant) andO_(subplant)−S_(subplant)produces≤d_(subplant) to the optimizationproblem such that d_(subplant) will be greater than or equal to thedifference between S_(subplant)produces and O_(subplant), regardless ofwhether S_(subplant)produces is greater than O_(subplant) or vice versa.These two constraints are functionally equivalent to a single constraint|S_(subplant)produces−O_(subplant)|≤d_(subplant) that requiresd_(subplant) to be greater than or equal to the absolute value of thedifference S_(subplant)produces−O_(subplant). However, replacing thisabsolute value constraint with the pair of constraintsS_(subplant)produces−O_(subplant)≤d_(subplant) andO_(subplant)−S_(subplant)produces≤d_(subplant) advantageously allows forall of the constraints to be linear, which reduces computation time.

At step 708, an optimization is performed on the objective function,subject to the override constraints above, to determine the amounts ofresources purchased, produced, discharged, consumed, and requested by aplurality of subplants over an optimization horizon. The optimization isalso performed subject to the balance constraints, operational domainconstraints, etc., as defined above. In some embodiments, theoptimization is performed on the objective function such that the totalamount of each resource obtained from sources 410 over the duration ofthe optimization horizon is minimized, regardless of cost or price, tominimize the total resource consumption of the central plant.

In some embodiments, the optimization is performed on the cost function,J(x), as defined above. The optimization of J(x) may be expressed as:

$\underset{x}{\arg \min}{J(x)}$

where J(x) is minimized over the optimization horizon such that theeconomic costs of operating an energy management system (e.g., assetallocation system 400), as defined by J(x), may be minimized (or theeconomic value may be maximized). The economic cost may account for thecost of resources purchased (e.g., from sources 410) as well as therevenue generated by selling resources (e.g., to resource purchasers 441or energy grid 442) or participating in incentive programs (e.g., IBDR,PBDR programs).

At step 710, the plurality of subplants (e.g., subplants 420) arecontrolled based on the results of the optimization. In one embodiment,a controller (e.g., central plant controller 500) may provide controldecisions to a BMS (e.g., BMS 506) on the amounts of resourcespurchased, produced, discharged, consumed, and requested by a pluralityof subplants (e.g., subplants 420), in accordance with the results ofthe optimization of the objective function. The control decisionsprovided to the BMS may include setpoints for the plurality ofsubplants, resource purchase amounts (e.g., for sources 410), and/orcharge/discharge rates (e.g., for storage 430). In turn, the BMS maycontrol the plurality of subplants to meet the control decisions. Forexample, the BMS 506 may command a subplant (e.g., steam subplant 424)to produce an amount of a resource (e.g., steam) based on the controldecision provided by central plant controller 500. Further detail on howcentral plant controller 500 control decisions may be implemented usingBMS 506 to control the plurality of subplants 420 is discussed above,where the control decisions generated by the central plant controller500 are based on the optimization of the objective function.

Referring now to FIG. 8, a flow diagram illustrates a cost impactdecision process 800, which compares the cost impact of multiple costfunction optimizations and presents a user with the cost impact ofoverriding a subplant load as a real value (e.g., dollars, kW, etc.),according to some embodiments. For example, while a user may enter anoverride value, allowing the user to operate a subplant at a specifiedload for a specified length of time, the override may cause suboptimalcentral plant operations. To mitigate suboptimal override decisionsand/or to display the effects thereof to a user, the optimization of theobjective function may be performed twice, once subject to the overrideconstraint(s) and once without an override constraint(s). The results ofthe two optimization may then be compared to determine a value (e.g., anincreased cost) associated with operating the central plant subject toan override constraint(s) on the production of one or more subplants.

At step 802, an objective function subject a balance constraint and anoverride constraint is generated. In some embodiments, the objectivefunction generated at step 802 may be subject to additional constraints,defined above. The objective function may be subject to a balanceconstraint, which guarantees the balance between resources purchased,produced, discharged, consumed, and requested by a plurality ofsubplants over a time horizon. Additionally, the objective function maybe subject to override constraints, also described above, which may be auser input that specifies the amount of a resource to be produced by oneor more subplants.

At steps 804 and 806, the generated objective function is optimized overa time horizon. At step 804, the objective function is optimized subjectto the override constraint, as described in step 708 of the optimizationprocess 700. At step 806, however, the objective function is optimizedwithout an override constraint. The optimization process of theobjective function when not subject to an override constraint isdescribed in detail above. Steps 804 and 806 may be performedsimultaneously or in succession by a component of the asset allocationsystem 400, for example.

At step 808, a cost impact of each optimized cost function iscalculated. The cost impact of the optimized cost function may bedefined as the cost, for example in currency (e.g., dollars, euros,yuan, rupees, bitcoin), associated with operating a central plant inaccordance with the optimization over the optimization horizon. In otherwords, the cost impact of each optimization result may be the total costpredicted by the objective function when the decision variables are setto values defined by the optimization result. The optimization of theobjective function performed in step 804 may result in a first costimpact, whereas the optimization of the objective function performed instep 806 may result in a second cost impact. In some embodiments, thefirst cost impact resulting from the optimization in step 804 is higherthan the second cost impact resulting from the optimization in step 806due to the additional override constraint in step 804. The calculationof the cost impact for each optimized cost function may be performed bythe asset allocator 402, another component of the asset allocationsystem 420, or the central plant controller 500. In other embodiments,the cost impact of each optimized cost function may be another realvalue, such as kilowatt hours or BTUs. For example, if the objectivefunction F(x) quantifies energy/resource consumption rather thanfinancial cost, the cost impact calculated in step 808 may be the totalamount of energy consumption or resource consumption associated witheach optimization result.

At step 810, a cost difference between the two cost impact results isdetermined. The difference between the cost impacts of the optimizedfunctions may be defined as the override impact. Continuing the examplefrom step 808, the override impact may be calculated by the assetallocator 402, another component of the asset allocation system 420, orthe central plant controller 500. The override impact defines theadditional cost of operating a central plant in suboptimal conditions(e.g., suboptimal resource production by a plurality of subplants of thecentral plant in accordance with a user's load override input). In otherembodiments, the override impact defines the additional cost ofoperating the central plant subject to a first optimization, subject toa first override constraint, over a second optimization, subject to asecond override constraint. For example, the cost impact as calculatedin step 810 may be higher when optimizing the objective function subjectto an override constraint as compared to the cost impact not subject tothe override constraint, as the override constraint may require asubplant to produce a suboptimal amount of a resource (i.e., the steamsubplant 424 producing an excess of steam due to an overrideconstraint).

At step 812, the cost difference (i.e., the override impact) ispresented to a user. The user may be presented the override impact via auser interface, where the user interface is implemented via a clientdevice 368, for example. Additionally, the building status monitor 524or the monitoring and reporting apps 526 may include a user interfacethat presents the override impact to a user. As described in detail inFIGS. 8 and 9, the user may be presented with an interface that displaysthe override impact as a dollar amount and displays what overrideconstraints may be contributing to the override impact value. By beingpresented the override impact, the user may see the economic or resourceuse impact of overriding a subplant or subplants of the central plantwhich may prompt the user to adjust or cancel suboptimal overrideconstraints. This may also reassure the user that the cost optimizationand asset allocation decisions made by the asset allocator 402 areoptimal, for example from an economic viewpoint.

In some embodiments, the user may be presented with a choice to operatethe central plant subject to the override constraint or to remove theoverride constraint and allow the asset allocator 402 to determineoptimal subplant operations. The plurality of subplants (e.g., subplants420) may be controlled based on the user's selection to operate subjectto the override constraint or without the override constraint, where theplurality of subplants may be controlled as in step 810 of optimizationprocess 800, described in detail above. In other embodiments, the usermay be presented with a choice to operate the central plant inaccordance with a first optimization, subject to a first constraint, orin accordance with a second optimization, subject to a secondconstraint, where the plurality of subplants may be controlled based onthe user's selection to operate in accordance with the first or secondoptimization.

Although process 800 contemplates comparing optimization subject to anoverride constraint to optimization without an optimization constraint,in other embodiments the process 800 is adapted to provide a comparisonof a first optimization subject to a first override constraint with asecond optimization subject to a second override constraint. Forexample, a first optimization of an objective function may be performedsubject to a first constraint, which specifies an amount of a firstresource to be produced by one or more subplants. A second optimizationof the same objective function may be performed subject to a secondconstraint, that specifies a different amount of the first resource tobe produced, and/or that specifies and amount of a second resource to beproduced. The results of the two optimizations can then be compared, asdescribed above.

Referring now to FIG. 9, an example user interface 900 is shown whichillustrates the production and storage load schedule across a pluralityof subplants when not subject to an override constraint, according tosome embodiments. This example user interface 900 may be presented viathe building status monitor 524 or the monitoring and reporting apps526, which may be implemented on the client device 368, for example. Auser may interact with the interface in a number of ways, such as byselecting a chart to view using the dispatch chart menu 902. The usermay also enter a start date 904 and end date 906, defining a period overwhich they would like to view data. The interface also includesproduction and storage items which may be selected for display. Thisexample user interface 900 allows a user to view asset allocations overa defined time period to monitor subplant and central plantoptimizations.

Referring now to FIG. 10, an example user interface 1000 is shown whichillustrates the production and storage load schedule across a pluralityof subplants when one or more subplants is subject to an overrideconstraint, according to some embodiments. Similar to the example userinterface 900, the example user interface 1000 may be presented via thebuilding status monitor 524 or the monitoring and reporting apps 526,which may be implemented on the client device 368, for example. A usermay interact with the interface in a number of ways, such as byselecting a chart to view using the dispatch chart menu 902. The usermay also enter a start date 904 and end date 906, defining a period overwhich they would like to view data. When one or more subplants aresubject to an override constraint, an override impact value may begenerated as previously disclosed in detail. The override impact may bepresented via the example user interface 1000, as shown by the overrideimpact graphic 1008. In this example, the override impact is shown to bea $500 increase over central plant operations that are not subject to anoverride constraint. Additionally, the example user interface 1000 isshown to include load override graphics 1010, which allow a user to viewa load that is subject to an override constraint in relation to theunconstrained loads.

Configuration of Exemplary Embodiments

The construction and arrangement of the systems and methods as shown inthe various exemplary embodiments are illustrative only. Although only afew embodiments have been described in detail in this disclosure, manymodifications are possible (e.g., variations in sizes, dimensions,structures, shapes and proportions of the various elements, values ofparameters, mounting arrangements, use of materials, colors,orientations, etc.). For example, the position of elements can bereversed or otherwise varied and the nature or number of discreteelements or positions can be altered or varied. Accordingly, all suchmodifications are intended to be included within the scope of thepresent disclosure. The order or sequence of any process or method stepscan be varied or re-sequenced according to alternative embodiments.Other substitutions, modifications, changes, and omissions can be madein the design, operating conditions and arrangement of the exemplaryembodiments without departing from the scope of the present disclosure.

As utilized herein, the terms “approximately,” “about,” “substantially,”and similar terms are intended to have a broad meaning in harmony withthe common and accepted usage by those of ordinary skill in the art towhich the subject matter of this disclosure pertains. It should beunderstood by those of skill in the art who review this disclosure thatthese terms are intended to allow a description of certain featuresdescribed and claimed without restricting the scope of these features tothe precise numerical ranges provided. Accordingly, these terms shouldbe interpreted as indicating that insubstantial or inconsequentialmodifications or alterations of the subject matter described and areconsidered to be within the scope of the disclosure.

The present disclosure contemplates methods, systems and programproducts on any machine-readable media for accomplishing variousoperations. The embodiments of the present disclosure can be implementedusing existing computer processors, or by a special purpose computerprocessor for an appropriate system, incorporated for this or anotherpurpose, or by a hardwired system. Embodiments within the scope of thepresent disclosure include program products comprising machine-readablemedia for carrying or having machine-executable instructions or datastructures stored thereon. Such machine-readable media can be anyavailable media that can be accessed by a general purpose or specialpurpose computer or other machine with a processor. By way of example,such machine-readable media can comprise RAM, ROM, EPROM, EEPROM, CD-ROMor other optical disk storage, magnetic disk storage or other magneticstorage devices, or any other medium which can be used to carry or storedesired program code in the form of machine-executable instructions ordata structures and which can be accessed by a general purpose orspecial purpose computer or other machine with a processor. Combinationsof the above are also included within the scope of machine-readablemedia. Machine-executable instructions include, for example,instructions and data which cause a general purpose computer, specialpurpose computer, or special purpose processing machines to perform acertain function or group of functions.

What is claimed is:
 1. A controller for building equipment that operateto provide one or more resources to a building or campus, the controllercomprising a processing circuit configured to: perform an optimizationof an objective function subject to an override constraint to determineamounts of one or more resources to be produced by the buildingequipment, wherein the override constraint overrides an output of theoptimization by specifying an override amount of a first resource of theone or more resources to be produced by a first subset of the buildingequipment; and control the building equipment to produce the amounts ofthe one or more resources determined by performing the optimizationsubject to the override constraint.
 2. The controller of claim 1,wherein: the first subset of the building equipment and a second subsetof the building equipment both operate to produce the first resource andcontribute toward a total amount of the first resource required by thebuilding or campus; and the optimization is performed subject to boththe override constraint and a second constraint that defines the totalamount of the first resource required by the building or campus.
 3. Thecontroller of claim 2, wherein performing the optimization subject toboth the override constraint and the second constraint comprisesdetermining a second amount of the first resource to be produced by thesecond subset of the building equipment based on a difference betweenthe total amount of the first resource required by the building orcampus and the override amount of the first resource to be produced bythe first subset of the building equipment.
 4. The controller of claim1, wherein: the objective function defines a total cost of operating thebuilding equipment over a time period; and optimizing the objectivefunction comprises determining amounts of the one or more resources tobe produced by the building equipment that optimize the total cost. 5.The controller of claim 1, wherein: the objective function defines atotal resource consumption of the building equipment over a time period;and optimizing the objective function comprises determining amounts ofthe one or more resources to be produced by the building equipment thatoptimize the total resource consumption.
 6. The controller of claim 1,wherein the optimization of the objective function subject to theoverride constraint is a first optimization and the processing circuitis configured to: perform a second optimization of the objectivefunction without the override constraint; calculate a difference betweena first amount of resource consumption or cost resulting from the firstoptimization and a second amount of resource consumption or costresulting from the second optimization; and present, via a userinterface, an override impact indicating the difference between thefirst amount and the second amount.
 7. The controller of claim 6,wherein the processing circuit is configured to: present, via the userinterface, an option for a user to select whether to use the overrideconstraint in view of the override impact; control the buildingequipment in accordance with a result of the first optimization inresponse to the user selecting to use the override constraint; andcontrol the building equipment in accordance with a result of the secondoptimization in response to the user selecting to not use the overrideconstraint.
 8. The controller of claim 1, wherein the overrideconstraint requires at least one of: an amount of the first resourceproduced by the first subset of building equipment to be equal to theoverride amount; or a difference between the amount of the firstresource produced by the first subset of building equipment and theoverride amount to be less than a threshold value.
 9. A method foroperating building equipment to provide one or more resources to abuilding or campus, the method comprising: receiving a user inputspecifying an override amount of a first resource to be produced by afirst subset of the building equipment; generating an overrideconstraint based on the user input; performing an optimization of anobjective function subject to the override constraint to determineamounts of one or more resources, including the first resource, to beproduced by the building equipment, wherein the override constraintoverrides an output of the optimization; and controlling the buildingequipment to produce the amounts of the one or more resources determinedby performing the optimization subject to the override constraint. 10.The method of claim 9, wherein: the first subset of the buildingequipment and a second subset of the building equipment both operate toproduce the first resource and contribute toward a total amount of thefirst resource required by the building or campus; and the optimizationis performed subject to both the override constraint and a secondconstraint that defines the total amount of the first resource requiredby the building or campus.
 11. The method of claim 10, whereinperforming the optimization subject to both the override constraint andthe second constraint comprises determining a second amount of the firstresource to be produced by the second subset of the building equipmentbased on a difference between the total amount of the first resourcerequired by the building or campus and the override amount of the firstresource to be produced by the first subset of the building equipment.12. The method of claim 9, wherein: the objective function defines atotal cost of operating the building equipment over a time period; andoptimizing the objective function comprises determining amounts of theone or more resources to be produced by the building equipment thatoptimize the total cost.
 13. The method of claim 9, wherein: theobjective function defines a total resource consumption of the buildingequipment over a time period; and optimizing the objective functioncomprises determining amounts of the one or more resources to beproduced by the building equipment that optimize the total resourceconsumption.
 14. The method of claim 9, wherein the optimization of theobjective function subject to the override constraint is a firstoptimization, the method further comprising: performing a secondoptimization of the objective function without the override constraint;calculating a difference between a first amount of resource consumptionor cost resulting from the first optimization and a second amount ofresource consumption or cost resulting from the second optimization; andpresenting, via a user interface, an override impact indicating thedifference between the first amount and the second amount.
 15. Themethod of claim 14, further comprising: presenting, via the userinterface, an option for a user to select whether to use the overrideconstraint in view of the override impact; controlling the buildingequipment in accordance with a result of the first optimization inresponse to the user selecting to use the override constraint; andcontrolling the building equipment in accordance with a result of thesecond optimization in response to the user selecting to not use theoverride constraint.
 16. The method of claim 9, wherein the overrideconstraint requires at least one of: an amount of the first resourceproduced by the first subset of building equipment to be equal to theoverride amount; or a difference between the amount of the firstresource produced by the first subset of building equipment and theoverride amount to be less than a threshold value.
 17. A controller forbuilding equipment that operate to provide one or more resources to abuilding or campus, the controller comprising a processing circuitconfigured to: perform a first optimization of an objective function todetermine first amounts of one or more resources to be produced by thebuilding equipment as a result of the first optimization; receive a userinput specifying an override amount of a first resource of the one ormore resources to be produced by a first subset of the buildingequipment; perform a second optimization of the objective function,subject to an override constraint based on the user input, to determinesecond amounts of one or more resources to be produced by the buildingequipment as a result of the second optimization, wherein the overrideconstraint overrides a portion of the result of the first optimization;and control the building equipment in accordance with the result of thefirst optimization or the result of the second optimization.
 18. Thecontroller of claim 17, wherein the processing circuit is configured to:calculate a difference between a first amount of resource consumption orcost resulting from the first optimization result and a second amount ofresource consumption or cost resulting from the second optimization; andpresent, via a user interface, an override impact indicating thedifference between the first amount and the second amount.
 19. Thecontroller of claim 18, wherein the processing circuit is configured to:present, via the user interface, an option for a user to select whetherto use the override constraint in view of the override impact; controlthe building equipment in accordance with the result of the firstoptimization in response to the user selecting to not use the overrideconstraint; and control the building equipment in accordance with theresult of the second optimization in response to the user selecting touse the override constraint.
 20. The controller of claim 17, wherein:the first subset of the building equipment and a second subset of thebuilding equipment both operate to produce the first resource andcontribute toward a total amount of the first resource required by thebuilding or campus; the second optimization is performed subject to boththe override constraint and a second constraint that defines the totalamount of the first resource required by the building or campus; andperforming the second optimization subject to both the overrideconstraint and the second constraint comprises determining a secondamount of the first resource to be produced by the second subset of thebuilding equipment based on a difference between the total amount of thefirst resource required by the building or campus and the overrideamount of the first resource to be produced by the first subset of thebuilding equipment.